A few week ago I had a healthy colony of predator zoas...about 4 days ago I woe to only having 3 eyes. this morning there was only one eye left. I decided to pull the small rock and put the last eye onto a frag and store it up high. Underneath the rock was a sand tube. Once I cracked open the tube this black thing was inside...Any ideas what it was, it was about 11/2" long.....past tense