Sea pigs are in reality a form of sea cucumber. They are echinoderms, marine animals that include the likes of starfish and sea urchins. Sea pigs are found in oceans all over the world and in some areas actually make up over ninety five percent of the weight of all the animals that can be found on the floor of the deep sea. Regardless of their number, the great majority of people are unlikely to ever set eyes on a sea pig as they live in the deepest and coldest parts of the ocean.

Sea pigs gained their name because of their pinkish, plump, oval-shaped bodies and their puffy legs. They are so small that they can actually fit inside the palm of a hand and are generally just four to six inches in length.

Scientists have been aware of the existence of sea pigs for over a century, having first been described in 1882 by the Swedish zoologist Hjalmar Theel. Sea pigs move about on the seafloor, having between five to seven pairs of tubular, enlarged feet that can actually be inflated and deflated in order to get around.