I am in the process of starting a seahorse tank. I came across some live rock that had been in an active tank (in the sump, not display) for about four years and it was reasonably priced so I bought it. I put it in the tank I plan on using for seahorses and it has several zoanthids and some red worms that resemble millipedes. It has a few strands of chaeto left on it. There are a few little tiny "bugs" that resemble roly-polies. I have not put any sand in yet, the rock was just hopefully a lucky find. I would like to know if this will be safe for the seahorses? I have scoured and searched and have not found the answer to this particular question so I hoped for some advice here. Thank you in advance.