The bell jelly is not a true sea jelly, but a hydromedusa. They have over 30-100 small tentacles that extend form their bells, which are usually less colorful that those of true jellies. They prefer to live in areas with little disturbance, including the ocean floor and calm harbors. On the ocean floor they eat benthic animals and often rise to the surface then sink back down collecting plankton to eat as they descend. Some species have light sensitive organs around the base of their bell which make a red ring around the base. The one found in California, Polyorchis haplus, does not. It is sturdier than the Polyorchis penicillatus and has 30 tentacles compared to P. penicillatus's 100 tentacles.
The images are of a P. haplus found on the beach, it was in a tide pool and of a live jelly in the ocean.