I'm pretty sure this is a type of salp. It was the most unusual thing I have encountered in the ocean. It was between half a meter and a meter in length.
Found off the Hopkins Marine station on a40 ft dive.
Purple slime on Duran beach. See "The Natural History of Bodega Head" blog, http://bodegahead.blogspot.com/2016/05/purple-pools-and-purple-waves.html?m=1
Floating around 9m deep off of San Carlos Beach Park, Monterey, CA
The Thaliacea comprise a class of marine animals within the subphylum Tunicata. Unlike their benthic relatives the ascidians, thaliaceans are free-floating (pelagic) for their entire lifespan. The group includes species with complex life cycles with both solitary and colonial forms.