Can’t quite tell so not 100% but from what you state and what I can see from the photos it seems like a NudiNoticed this guy coming out of the rocks at night. I need some help with ID. Is this a flatworm or a nudibranch? It has 2 small antennas that it retracted as soon as I pulled the camera out.
Thanks. He doesn't seem to irritate anything but didn't know if he was a good guy or not
Some Nudis are beneficial and some are harmful so I’d suggest you look up what exact type of Nudi it is and if it’s compatible with everything you’ve got
