In New LeafEdit
Upon donating a Sea Urchin to the Museum, it can be found in the large pool in the first room of the Ocean exhibit, along with many other species of deep sea creature. It is found in the part of the pool closer to the entrance to the saltwater exhibit. The exhibit has this to say about the Sea Urchin:
"Sea urchins are a close relative of both starfish and sea cucumbers and are assumed to be stationary. In actuality, they are capable of walking thanks to their many skinny legs they have between their spikes. They feed on seaweed on the ocean floor using their strong mouths located on their undersides. They are rich in nutrients but also have a lot of cholesterol, so take care not to eat too much."