it's a sea creature. Probably toxic. (See below.)
But it's got a BIIIIG SMILE (they way I see it:)
Photographer: David Doubilet, who, not by chance, has many other famous and thrilling, exotic under-da-sea photos (like this one).
The species above or rather, genus, is Chromodoris, and it's a nudibranch.
Also of note, as a spinoff:
Through countless media interviews, books, testimony before Congress, and on public, private, and academic stages worldwide, she [Sylvia Earle] strives to help us understand the consequences of everything we put into and everything we take out of the ocean—noting that every breath of air we take and every drop of water we drink depends upon its health. (Link here.) Funny enough, at the bottom, you'll find her interview with Stephen Colbert, in the Colbert Report.