so what is a nudibranch? a soft naked sea slug. From Wikipedia:
A nudibranch // is a member of Nudibranchia, a group of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms. There are more than 3,000 described species of nudibranchs.
The word "nudibranch" comes from the Latin nudus, naked, and the Greek βραγχια, brankhia, gills.
Nudibranchs are often casually called sea slugs, but many sea slugs belong to several taxonomic groups which are not closely related to nudibranchs
NatGeo has a photo gallery here
Photograph by Jennifer HayesBuilt to feed exclusively on corals like this spindly gorgonian, a translucent 1.7-inch-long Phyllodesmium iriomotense houses its branching digestive gland within tentacle-like cerata—outgrowths the animal can shed if under attack. This species is one of the few colorless nudibranchs.
and this one looks like Smaug:
Size: 1.2 in (3 cm)
and if you google "Philippine nudibranch" you can find where you can view them, plus lots more photos.
update: Sea Slug forum has lots of information and links.
And I can't find recipes; Some excrete a poisonous mucus which can cause problems if you get one in your saltwater fish tank. But this site says that the Orange Peel seaslug can be eaten.