what's up with this?

I'm glad this got bumped back up because I have an update on this topic. Mine basically has split apart at the point of original stress. I now have two perfectly healthy toadstools that are hardly attached to each other. I'm now at the point where it will basically break off so I can simply scissors the small one off the rock and rubber band it to a new rock. I'm pretty sure this is how they propagate in the natural setting as well.