Ok. Will try that now. Here goes. This sure isn't for the faint of heart.
Soaked him in warm running water. The bottom of the shell came off, with a lot of runny liquid. Because of where the membrane is stuck on the face, I couldn't get it off with water without getting it in the nostrils. Nothing is bleeding anywhere, but this membrane stuff is rock hard on his face. He's quite a wiggler and fighter.
You can use a moist q-tip, paper towel or wash cloth to get the stuff off it's face, but make sure it doesn't get chilled.