Dorsal and ventral chitinophosphatic valves of deep-water of Pelagodiscus atlanticus (Kuzmina & Temereva, 2019). (A) Dorsal view of the fixed animal: the dorsal valve (dv) with long setae (ls) is visible. (B) Ventral view of the fixed animal: the ventral valve (vv) is partly open, and the mantle cavity (mc) contains two lophophoral arms (lam). (C) View of the ventral valve (vv) with short setae (ss) and a round pedicle (p). first-formed region of the shell.