So I bought a fighting conch to help keep the sand clean. For the first couple weeks he was awesome, worked as advertised (aside from rearranging my corals for me) then he just vanished. I finally found him after a week buried in the sand. I dig him out, he roams for a bout a day and does the same thing again, He just goes under the sand and just stays there, I think the record was 2 weeks, before I had to check to make sure he wasn't dead. Any idea whats going on with this guy?