This species of Amphidinium (am-fee-din-ee-um) contains a plastid with chlorophylls a and c (the yellow/brown colour indicates this). All taxa with plastids of this colour have been considered by some to form a group - the Chromophyta or chromists which has at times included some unrelated organisms. It looks as if there is a single radiating plastid. It has a pyrenoid, as another image of the same species shows. Circumferential groove is located near the top of the cell. Differential interference contrast.