Undulated, waved, having a waved surface.
Ungulate, shaped like a horse’s hoof.
Unilocular, with a single chamber or compartment.
Univalve, shells consisting of one valve or piece.
Volutions, the wreaths or turnings of the shells of univalves.
Urceolate, swelling in the middle like a pitcher.
Vulva, a spatulated mark in several bivalve shells; formed when the
valves are united on the posterior and anterior slopes.