Mushroom Help?

[Quiksilver737]

I recently purchased a rock covered with about 12-15 blue mushrooms. Most of them seem to be doing fine, although there is a translucent brown slime-like thing attached to the rock as well. I can't tell whether this is a mushroom or something else. Any ideas?

I attached two pictures. One is a close up of the unknown slime, the other is a picture of the whole rock. It is in the middle right above the big piece of coralline algae.