several different methods. all involve using a sharp razor blade.
1. slice the cap clean off the stalk. use a mesh netting and secure it to some rubble. the cap will; adhere and grow a new stalk. and the stalk pieces that are left on the original rock will grow a new cap.
2. slice the mushroom down the center to the rock trying to get a piece of the mouth in each section. you can do it once to cut it in half or twice to make quarters. 95% of the time they will grow into new shrooms. sometimes they will grow back together.
3. cut the cap off and let it float around. where ever it lands you will get a new mushroom colony.
4. cut the cap. put it in a blender. turn on. pour back into tank. presto - instant mushroom overload. each piece can theoretically create a new muhroom.
don't worry. it is very easy to do.
oh yeah. they also stink!!!!