Bubble-shaped shell, fragile, translucent, smooth, with no traces of ornamentation. The margins of the elongate aperture extends beyond the spire. Animal somewhat elongated, too large to be fully retracted into the shell. Cephalic shield deeply bifurcate posteriorly and divided into a pair of well-developed flaps. Parapodial lobes short, reflected over anterior half of shell and not meeting dorsally. A large posterior pallial lobe enclosed the posterior end of the shell.
shell translucent, whitish or creamy white. Background color of soft parts greenish white, with many patches of cream-whyte, and with some yellow blotches sprinkled over. Margins of the mantle purple-blue, contrasting strongly with the pale ground color of the animal. The purple blue line breaks up into a series of bluish spots in the anterior margin of the head. A large bluish spot separate the two eyes. Some dark purplish blue spots are also visible beneath the shell.
common size :
animal size from 5 to 15 mm, shell up to 10 mm.
The conspicuous purple-blue margin of the animal distinguishes Haminoea cyanomarginata from all other Mediterranean species of this genus.
BIOLOGY / ECOLOGY
Unknown. Like other species of this genus, probably feeds on diatoms and on filamentous algae.
in the Red Sea it has been found amongst coral rubble in shallow waters. In Greece and Turkey, usually seen at night between 15-30 m of depth on rocky surface covered with algae.