I have had my setup for over 1.5 years .I thought of getting something new for the tank .I said I'm done with zoas...they never seem to survive in my tank ...they seem to disappear eventually,little by little.To my surprise I see this thing moving underneath a rock and it was a big ugly gorilla crab(I found out later through research).So I was kind of excited to find something new that big that I wasn't aware was there before.So I built a trap-no luck though- and I went on a night watch with a flash light and was amazed to see the tank teaming with life (pods,bristleworms,worms).I think I enjoyed my tank last night more than any other time.I will try to get pictures of the crab when caught.