Is this a sponge?

[ACBlinky]

I bought a candycane a while ago and something has grown off it, attaching it firmly to the rock. I'm wondering if it's a sponge?

Here are some pictures - it's the mustard coloured area in the bottom left of the first picture, centre of the second.

 

[The steven liu]

It does look like sponge but not 100% sure.