Indonesia is a nudi lover's dream. There were many, many nudibranches around, some of which were almost breathtaking in beauty.
I enjoyed particularly the spindle cowries, sitting perfectly camouflaged on its host gorgonian. The first one that John pointed out to me confused me for a moment. Why was he pointing to a fat part of the gorgonian? Upon closer inspection, I saw the cowrie. Amazing.
Also bizarre are tiny little flatworms that we found on a leather coral. They looked like tiny brown stains, but they moved around quite quickly if disturbed. My reef tank friends say that these flatworms can take over your tank (in a bad way) if introduced.
Interested in sea slugs? Try the sea slug forum.