I caught a sea urchin at a low tide and since they were rare here and my first time seeing one i grabbed him home and now here I am questioning my decision on wheather I can care for him or not, tanks 210g I have a tessalata in there aswell as some yellow tail damsels and a lunar wrasse which I am trying to get out, I added the urchin and Upon instant he was really active and already started moving around, i wanted to know what species he was and what those white tentacles moving around besides his thorns were