I don't know if this is the correct place, but I've been looking for someone that could help me identify this creature I found while I was looking for shells. There are three mollusk-like "beings" stuck in some sort of big seed (it's definitely not a rock nor a part of their body). They can "spin" around with the arm that is stuck in the seed, and they continuously take some blood red hair-like tentacles in and out of a shell. I shot a video of it, the link is right below. Please ignore all background audio, I couldn't find somewhere without people. This "being" was found today, at roughly 6pm, washed ashore in the beach I'm visiting - "Praia Grande" in Brazil. Another peculiar thing is that tap water makes the "things" close for a while, and sea water doesn't do much. Also, as they dried, the single tentacle hair became multiple smaller ones. They keep coming in and out, without stop.
If anyone could give me a shine on what that animal is, it would be super helpful!