Title photo by Michaels Bubbles

Cyerce nigra is well-known for its cerata that resemble overlapping leaves or a ruffled ball gown.

It is found in the Central Pacific, Palau, Papua New Guinea, Philippines, and grows to 15mm to 30mm in size

Above photo by The Three P Beach Resort Romblon

Above photo by elebe.foto

The dorsal surface features alternating black and white/yellow stripes.....

Above photo by Ludovic

.......while the ventral surface has orange or yellow spots on a black background.

Above photo by rob jeff

Both sides have an orange or yellow edge with two faint black and white lines.

Above photo by Rickard Zerpe

Above photo by touchement

On its head are forked receptors that are hollow halfway through and have the same striking colors, but with a different pattern.

Above photo by Ludovic

Above photo by Patrick Ess

[It]....lives on [the] sandy bottom, on algae fields in shallow water or seldom on coral fields...

Above photo by AGNIESZKA ADAMCZYK

...[It] feeds on algae genus Udotea, especially on Udotea geppiorum

Above photo by joycelynchang

Info from here and here

edit, forgot to add location and size!

2nd edit- forgot to add a link!