Turkish artist Elif Ayiter (aka Alpha Auer) created an underwater fantasy (or nightmare) next door to her island of Syncretia in Second Life. She says it frightens her, and hasn't been able to explain it yet.
http://www.lookatme.ru/flows/fotografiya/posts/77179-subaquatic-beauty-by-alix-malka
Never found out what the shrimpy thing was
There was a school of fish swimming behind the sea grass, but that wasn't a successful (IMHO) element to the overall scene.