ˈtrōkəs noun
Etymology: New Latin, from Latin, wheel, iron hoop, from Greek trochos wheel — more at troch-
1.
a. capitalized : a genus of chiefly Old World tropical marine gastropods (family Trochidae) with beautifully nacreous bluntly conical shells including a large Indo-Pacific species ( T. niloticus ) extensively used in making buttons and ornamental objects
b. -es : top shell
2. plural tro·chi -ōˌkī or trochuses : the inner preoral band of cilia of a trochal disc ; broadly : trochal disc