I can't quite make out pic #4 but they almost look like a colony of tunicates. If it is a bunch of indiviual "chambers" with two vents in each then it is likely a tunicate. Does it look kinda like this?
http://images.art.com/images/-/Micha...C10255325.jpeg
If got small, purple individual tunicates in my tank. Harmless and cool.