My experience with majanos and the killing of them...
I bought a frag rock with some on it. I wanted to do the pickeling lime thing but couldn't find any. So, I bought a hypodermic needle from the Rx, placed the rock in a tupperware bowl next to the stove and injected boiling water into them. Done and have not seen them since.
I then had to do it to aiptasia that I brought home without knowing it. In this case I couldn't remove the rock, so I did a mad dash between the stove and the tank. Although it cools rapidly, it was still hot enough to kill them.
My Mom told me not to run with scissors, but she didn't say anything about not running with hypodermic needles. 
Good luck.