Thuridilla coerulea from Andaman, India.

Thuridilla coerulea from Andaman, India.
Photographer: Bhave, Vishal

Size: 12-18 mm.

Depth: 0.3 m

It is rediscovery after its description from ceylon, though it is mentioned in quite a few publications.

http://www.seaslugforum.net/factsheet/thurcoer