For thousands of years, a natural sponge was simply what people used to wash. Today most sponges in kitchens and bathrooms are synthetic foam, but natural sea sponges are still sold for bathing, skincare, painting, pottery and cleaning, and many people prefer them for their softness and durability. If you have ever wondered what the different types are, where they come from and whether they are worth the price, this guide covers the main commercial sponges and how they compare.

Key West, one of the places I’ve dived, was once the centre of Florida’s sponge industry, built on the same Gulf and Caribbean species described below. As someone who spends a lot of time looking at living sponges underwater, I find it worth remembering that every natural bath sponge was once a living animal on a reef or seagrass bed.

What makes a sponge a bath sponge?

Most of the world’s more than 9,000 sponge species would be useless in a bath. Only a handful have the right skeleton.

Most sponges build their skeletons from tiny glassy or chalky needles called spicules, which make them scratchy or brittle. A small group of demosponges, mainly in the genera Spongia and Hippospongia, have skeletons made almost entirely of spongin, a tough, flexible, collagen-like protein arranged in a fine three-dimensional mesh. When the living cells are removed, that mesh stays soft and springy, holds a lot of water and releases it when squeezed, and lasts far longer than you might expect. Our page on sea sponge structure explains spongin and spicules, and are sea sponges alive? covers the difference between the living animal and the product.

Caribbean and Florida sponges

The western Atlantic sponge trade, centred on Florida, the Bahamas and Cuba, traditionally recognised several grades.

Sheepswool (Hippospongia lachne), often sold as “wool sponge”, is the most prized. It is large, soft, absorbent and very durable, with a woolly texture and large internal channels, making it popular for bathing, washing cars and boats, and cleaning. Yellow sponge (Spongia barbara) is firmer and finer-textured, good for bathing, crafts and applying finishes. Grass sponge (Spongia graminea) is coarser and cheaper, used for cleaning, painting textures and industry. Velvet sponge (Hippospongia gossypina) is soft but less durable than sheepswool. Smaller, finer types such as the glove sponge were also traded. These sponges grow on hard bottoms and seagrass flats in shallow, warm water; see sponge diving for the history of how they were collected.

Mediterranean sponges

The Mediterranean has the oldest sponge trade in the world and is the source of some of the finest sponges.

Silk sponges, also called fina or Turkish sponges, come from Spongia officinalis and related forms. They are small, dense and extremely soft, with very fine pores, and are prized for facial care, makeup application and delicate skin. Honeycomb sponges (Hippospongia communis) are larger and rounder, with big holes like a honeycomb, and are popular for bathing because they hold plenty of water. Elephant ear sponges (Spongia agaricina) are thin, flat and ear-shaped, and are favoured by potters and painters for smoothing clay and creating textures. Greece, Turkey, Tunisia and Libya have long been the main sources; see Mediterranean sea sponges.

Sponge	Scientific name	Region	Texture	Best for
Sheepswool (wool)	Hippospongia lachne	Florida, Bahamas, Caribbean	Soft, very absorbent, durable	Bathing, car and boat washing
Yellow	Spongia barbara	Florida, Caribbean	Firm, fine	Bathing, crafts, finishes
Grass	Spongia graminea	Florida, Caribbean	Coarse	Cleaning, paint effects
Velvet	Hippospongia gossypina	Florida, Caribbean	Soft, less durable	Bathing
Silk (fina)	Spongia officinalis	Mediterranean	Very soft, dense	Face, makeup, babies
Honeycomb	Hippospongia communis	Mediterranean	Soft, large pores	Bathing
Elephant ear	Spongia agaricina	Mediterranean	Thin, flat, fine	Pottery, painting

How bath sponges are harvested and processed

Commercial sponges are collected by divers or hookers and then cleaned on shore.

Responsible harvesters cut a sponge above its base, leaving the attachment point and some tissue so the sponge can regrow, and leave undersized sponges to reproduce. The harvested sponges are left in the shade or in shallow pens so the living tissue dies and decays, then they are squeezed, beaten, washed and rinsed repeatedly to remove the decayed cells, sand and shell fragments. After drying, they may be trimmed into neat shapes, and some are bleached to a pale colour; unbleached sponges are usually tan or golden. Bleaching makes a sponge look cleaner but weakens the fibres and shortens its life, so many people prefer natural, unbleached sponges.

Natural sponges vs loofahs and synthetic sponges

Three very different things are all sold as “sponges” in shops.

A natural sea sponge is the protein skeleton of a marine animal. A loofah, or luffa, is the dried, fibrous interior of a gourd in the cucumber family, grown on vines; it is rougher and is used as an exfoliating scrub. Many people are surprised to learn that a loofah grows on a vine in a garden rather than on a reef. A synthetic sponge is made from plastic foam such as polyurethane, or from cellulose derived from wood pulp. Natural sea sponges are softer than loofahs, more durable than many synthetic sponges and biodegradable, but they come from wild animal populations. Synthetic sponges are cheap and consistent but can shed microplastics; cellulose sponges are a plant-based middle ground.

How to tell a real sea sponge from a fake

Synthetic sponges are sometimes moulded and coloured to look natural, so it helps to know what to check.

A real sea sponge has an irregular shape, no two exactly alike, and a network of channels of different sizes running through it rather than uniform bubbles. Look closely at a cut face and you will see a fibrous mesh rather than foam. Real sponges are usually tan, golden or creamy if unbleached; very white sponges have been bleached, and bright colours almost always mean dye or a synthetic product. When dry, a real sponge is light, stiff and slightly crunchy; when wet, it becomes soft and springy and expands noticeably. A faint marine smell when first soaked is normal. Synthetic foam, by contrast, has evenly sized cells, often has smooth moulded surfaces and stays the same size wet or dry.

Beyond the bath: sponges in art and pottery

Natural sponges remain popular tools in several crafts because synthetic versions cannot quite match them.

Potters use thin elephant ear sponges and fine silk sponges to smooth and compress clay on the wheel, soften edges and wipe glaze. Painters and decorators use sea sponges, especially grass and wool sponges, to create mottled textures on walls, a technique known as sponge painting, because the irregular structure leaves a natural, uneven pattern. Makeup artists use small silk sponges to apply and blend foundation. Watercolour artists use them to lift paint and create clouds and foliage effects. In each case, it is the irregular, open mesh of spongin that does the job, the same structure that once channelled seawater through a living animal.

How to care for a natural sponge

A well-cared-for natural sponge can last a long time. A neglected one goes musty quickly.

Before first use, soak the sponge in warm water to soften it and rinse out any remaining sand. After each use, rinse it thoroughly in clean water, squeeze out as much water as possible without wringing or twisting it hard, and leave it to dry completely in a well-ventilated spot, out of direct sun and away from a damp shower floor. Every week or two, soak it for a few minutes in water with a little vinegar or baking soda to freshen it, then rinse well. Avoid bleach, boiling water and the dishwasher, all of which damage spongin. Replace the sponge when it starts to break apart, smells even after cleaning or becomes slimy. Do not use a natural bath sponge internally; see menstrual sea sponges for why.

Are natural sponges sustainable?

They can be, if harvested carefully, but sponge populations have collapsed in the past.

Because sponges regrow from cut bases and fragments, well-managed harvesting can be sustainable, and sponge farming, growing cut pieces on lines in the sea, has been tried in several places. But wild sponge beds have been badly hit by overharvesting and disease. A disease outbreak in the late 1930s killed most commercial sponges across the Caribbean, the Bahamas and Florida, and another devastated Mediterranean beds in the 1980s. Buying from suppliers who explain where and how their sponges are harvested, and choosing unbleached, minimally processed sponges, are good steps. Sponges are also important animals in the wild, filtering water and sheltering other species; see sea sponge facts.