Appearance
The shell of A. cornuta is quadrangular to obliquely trigonal. It attaches itself to surfaces during its early growth stage, after that it is free-living. The shell features seven to nine radial rows of pleated radial ribs covered by large spines with coarse pitting between ribs. The exterior is a creamy white color with the interior being white with flushed pink and/or yellow coloration. The typical habitat is that of coral reefs.