Halgerda wileyi

Seen in Malapascua, Philippines (2012). Photo by Mark Bockstael (my husband).
Halgerda willeyi is a species of sea slug. It is a dorid nudibranch, and shell-less marine gastropod mollusk in the family Discodorididae. The body of the Halgerda willeyi is rigid, with soft curves and various colours. White or gray with interconnected yellow-topped ridges and numerous black and yellow lines between. This species is a fairly large halgerdid, and can reach 8 cm. Halgerda willeyi can be found throughout the western Indo-Pacific, including Taiwan, Vietnam, Myanmar, Egypt, Indonesia, Malaysia and Australia and in the Red Sea.