What, eating it's mantle? Yes. A clams partial means of survival is what the Zooxanthellae feed the clam. If the clam starts running out of area to house Zooxanthellae - it can cause the clam to bleach out, not feed, not get nutrients, get stressed, just ALL KINDS of stuff. Think of it's mantle as like a solar energy panel that runs an entire house. What happens if you start to break chunks of it off?