I was planning not to make an account here for around another year, but it seems like a certain hitchhiker had other plans. I got a new live rock for my 10 gallon reef aquarium today, and when I was placing the rock in, I saw something brown and squishy with arms with suckers, and it grabbed my glove. After that, it retreated into the rock. Other than that, I also some bristle worms and brittle stars, although they were definitely different than what I first saw. Any advice is welcome, I can move up to a 38 gallon bowfront whenever needed, and I can get a 50 after that. I plan on trying to look again tommorow and feed it some live brine I happen to have, and I'll take appropriate measures to seal my tank.