their gonads are found through a single genital orifice on their dorsal anterior end. their digestive system is made up of a mouth, an esophagus, a stomach, an intestine, a cloaca, and an anus. they extend respiratory trees from their cloaca in order to breathe. their body wall is thick, making up a total of 56% of their weight. this body wall is filled with calcareous plates called spicules, and are used to id species; the sandfish is identified by table and knobbed button shapes. like other sea cucumbers, they can eviscerate their internal organs if they undergo stress, and can regenerate their organs; in sandfish this takes about 2 months.