Architectonica trochlearis
Architectonica trochlearis is a species of sea snail, a marine gastropod mollusk in the family Architectonicidae, which are known as the staircase shells or sundials.
Description
The diameter of the shell attains 40 mm.The shell is orbiculato-conoidal and is somewhat depressed. The whorls are somewhat swollen. The whorls of the spire are longitudinally folded, while the body whorl is smooth. They are divided superiorly by a single groove. The uppermost area is banded with dark-brown, and it is encircled below with quadrate dark-brown spots. It is keeled at the periphery and articulately ornamented with white and dark-brown spots. The base is a little swollen. The umbilicus is large and wide-open, possessing somewhat acute brown crenations.