Berthellina citrina reaches 6 cm. Small opisthobranch mollusk (Pleurobranchidae) Indo-Pacific and Mediterranean with stocky uniformly distinctive lemon-yellow body (hence citrina), small reduced internal shell. Lives from 1 to 30 m under stones and in rocky crevices of coral and rocky reefs of entire Indo-Pacific and Mediterranean. Nocturnal, ascidian predator. Accessible macro photo subject for its uniform vivid yellow pattern.
