Stupid Cuttlebone

The Cuttlebone I had bought before floated like a cork for as long as it took for Squirt to eat it. I ran out of that cuttlebone, So I had to buy a different one. This new one, I removed the backing and all, then break off a chunk, and throw it in the tank. I wake up the next morning to see it sitting on the sand, Sunk. 

Stupid thing didn't even last a day without sinking. I'm probably just going to give the rest of this cuttlebone to the Ornate Boxie, then just go buy a better cuttlebone and hope it doesn't sink.