We saw several Haliclystus sanjuanensis (Stalked Jelly) attached to seaweed during the -2.1 tide. It's a bit over 1/2" across. (Still learning how to use my underwater camera.)
Snorkelingtrip.
the tentacles would spring up and fall back down much like the tentacles of a blue bottle jellyfish but there is no bell & it seems to have some sort of tail.