Scutellastra optima

The shell of the holotype measures 64 mm × 80 mm (2.5 in × 3.1 in).^[2]

(Original description) The shell is large, solid, and ovate in shape, with a distinctly depressed profile. Its sculpture consists of numerous low radial riblets, which are approximately equal in width to the intervals between them. These riblets are layered over a coarser underlying structure of about a dozen low, broad radial elevations.

The color is striking: the depressed spaces between the primary elevations are a dull, deep maroon, while the smaller intervals between the riblets on the raised portions exhibit a diluted shade of the same hue. The interior is white, featuring a central field clouded with cinnamon tones. ^[2]

Scutellastra optima occurs in the northwestern Pacific.^[3] The holotype was obtained from Yakushima (Japan).^[2]

Nakano T. & Ozawa T. (2007). Worldwide phylogeography of limpets of the order Patellogastropoda: molecular, morphological and paleontological evidence. Journal of Molluscan Studies 73(1): 79–99.