I've been using a microwave to clean shells ever since I bought my wife one
(at least that's what I told her) in 1979. Never had a problem, except that
at times the end of the animal did not blow out. It was cooked and as a
result rotted slower, if you can call it that. Actually over years it just
got real hard and dried up. Microwave use is not for all shells, but those
really hard to get Conus, terebra, Mitra, Murex, etc., it seems to work
great. Just ask my wife, she loves her microwave, when I'm not cooking up
something special.

I don't set the timer, I just wait for the pop sound. Also best if done one
shell at a time as different shells have different cooking times.

Frank (Looking forward to Spring and it hasn't even snowed yet)