I keep coming across those weird... things... in an area where I go snorkeling sometimes, but I have no idea what they are. Really weird anemones, maybe?

I've only ever seen them attached to rocks, usually in the intertidal zone, but I've seen some in a spot that's constantly underwater. They seem to prefer areas beneath little rocky overhangs, so I'm guessing they're not big fans of sunlight and can't cope well with too much heat. I haven't been able to see any visual differences between those that were submerged and those that weren't, such as desiccation or retracted parts, but I didn't get a super good look at the submerged ones. I estimate that each "tentacle" (not sure what to call those) is maybe 1.5 cm long at most. I didn't see any of them move on their own, but I wouldn't rule out that that could happen. The pictures I've taken represent the color range I've seen pretty well.
For further context, the area where I found that is within a bay that has been greatly impacted by human activity, and the possibility that it's exotic exists. Also, I first came across it a few months ago and today it was still there, with no immediately noticeable changes, based off my memory.

I honestly have no clue what that is, so even a very vague idea of what larger group it might be in would already be helpful.

TIA :)