sea urchin - echinus melo
The mouth of most sea urchins is made up of five jaws, with a fleshy, tongue-like structure within. The mouth and anus of a sea urchin is found at the bottom of the creature. The lantern, the shape of the sea urchin's mouth and anus area, (named by Aristotle) when present, surrounds both the mouth and the pharynx. At the top of the lantern, the pharynx opens into the esophagus, which runs back down the outside of the lantern, to meet the small intestine and a single caecum or pouch. The small intestine runs in a full circle around the inside of the test, before joining the large intestine, which completes another circle in the opposite direction. From the large intestine, a rectum ascends towards the anus. Despite the names, the small and large intestines of sea urchins aren't the same at all to the similarly named structures in other organisms.