moving clam

I moved some rock work around the other week, just minor adjustments. I guess one of my maxima's didn't agree with the changes and jumped 10" down to the bottom of the tank. I moved him up to the rock, and again he jumped off. So I thought I would leave him on the sand till I found another spot for him. The problem is that while he has been on the sand he dug past the rocks I had burried under him and has now attached to the glass on the bottom of the tank.
Should I try and move him? I just don't know if he'll get enough light 24" down. He's half attached to the glass and half to one of the peices of shell of rock. Should i use a razor to cleanly scrape him off the glass?

 

I would just leave it where it is but if you absolutely must move it, get a razor blade and cut the byssal threads working as close to the glass as possible.