its not the first time ive heard it done, even with the risk of spreading!
u might have be steady& more to the point lucky & not actually damaged the membrane for the
kalk to do its caustic working of the spore jackets! but honestly, how much less risky is that, than letting a crab get there mits on them! crabs attach first ask questions latter, they may eat them but bursting the membrane to spill the contents is still the same thing! honestly, at risk of sounding strange, just pull the piece out thats attched to the rock, grab a chissel and cut a slitther off the rock from underneath it! add your rock back! even if it does succumb, its out of the tank anyways!