Purple fleshy stuff on the rock

[Conway23]

I noticed a while back that underneath my green mushroom frag there was some purple fleshy like stuff growing on the piece of rock. When I upgraded my tank a month ago it had grown all around the frag piece. It is now starting to grow on to my main rock work and I have no idea what it is. I know it isn't coraline because it's soft to the touch.
I've tried to get the best pic that I could, has anyone got any ideas?

 

[ReeferMaddness843]

Can't really tell in pic. But based on description, I would say a purple sponge.

 

[Katrina71]

I have a smaller version. Good guys.