From the Bali files. This is the front end of a teensy Doto nudibranch, feasting on a hydroid.
There are thousands of species of nudibranchs (aka sea slugs), and they come in a kaleidoscope of colours and patterns. Big nudis can be up to a foot long. This little beauty (Doto greenamyeri for all you nudi geeks out there) was about 1/3 of an inch in length. Those horn things (rhinosphores) are how they smell/sense. Shot with a 60 macro lens and a +10 diopter, plus a whole lotta cursing .