My best guess would be a type of sponge. It's fairly common and if you search for "Zoas sponge" in the forum there are several instances with a variety of different types of sponge.
As far as I know they're generally harmless other than their physical presence potentially smothering coral.
I am not sure how to best approach removal.
I dont know what really could be the problem on the left zoa cluster, possibly a sponge? With the right, obviously that's bubble algae. Assuming you have no other bubble algae anywhere else in your tank, i would just pull that zoa plug and clean it off manually. I'm sure someone on here knows exactly what that is on the left one... sorry i dont.