Phoenix Rising I have several ways of removing them.
1. Point a powerhead directly at them, They will start to crawl eventualy, place a piece of slate or flat rock on bothe sides, when they crawl on it pick it up.
2. Hold the rock they are on just out of the water, so one tentacle can touch they will let go with there feet and start to slide towards the water, then it is easy to remove them with out tearing there foor.
3. With you thumbs rub the base until it starts to move, then do same as last part of numbe 2.
J21- You can --- them by looking under their skirts
Just kidding, if you hold them up to a light you can actually see their reproductive organs. I force them to split By removing them from the water and sticking them in a bucket with no current, and let the temp drop about 2-5 degrees, then stick them back in the tank, and rais the tank temp about 3 degrees. It stresses them into splitting. When I ge the 55g set up, I will do massive water changes instead. 50% with lower or higher slainity, and different temperatures.