Only thing I can think to do would be to remove it from water, try and pry/wedge the mushroom off (either with something like a credit card or the dull end of a razor blade) and spare the shell and hermit. Have some superglue handy, and reglue the mushroom to a piece of rock rubble or something else. Should work just fine. Good luck!
Live in the Western MD/West Virginia/DC Metro Area?
Join our very active regional forum Here
Like the advice someone just gave you? Add to their reputation! Click on the balance icon underneath their username and let them know.