About Trimusculus conicus (Angas, 1867)
Trimusculus conicus (Angas, 1867) has an ovate, conoidal shell that is typically depressed, marked with radial ribs, and has an apex positioned rather posteriorly. The shell's sculpture is made up of around 40 nearly equal, narrowly rounded straight riblets, some of which do not reach the summit. Concentric growth lines are present in most individuals, and they very often form distinct prominent ridges. The exterior of the shell is white, with a light pinkish tint near the margin; the shell's interior is white, also with a light pink margin. The apex ranges from subcentral to nearly marginal; it is small and distinctly hooked (uncinate) in well-preserved specimens. The anterior and side slopes of the shell are convex, while the posterior slope may be straight, concave, or slightly convex. The interior of the shell is shiny, with the adductor scar and siphonal groove clearly visible. The shell margin is very slightly crenulate. This species has two common shell forms. The low form reaches up to 26 mm in length, 22.5 mm in width, and 8 mm in height. The high form reaches up to 22 mm in length, 18.5 mm in width, and 15 mm in height.
