Starfish Outbreak!!

[Scavenger]

This is a new one for me, I'm curious if anyone has seen this before. It's been at least half a year since any corals or rock have been added to my aquarium. (Just fish)
But today while doing a small bit of re-aquascaping, I noticed a small white starfish (about 1/2 the diameter of a dime) on a rock. I pulled him out and set him into a glass of water until I could get an ID.

Anyway, after giving the tank a quick looking over, I've counted 9 of them without much effort so there must be more. The biggest being about the diameter of a nickel. They are similar in shape to the starfish we see here on the BC beaches just way smaller and white with black/grey mottle. Some are missing legs ect. So I wonder if one starfish got chopped up and regrew???

None of my other livestock is showing any stress or ill effects, so they aren't eating my coral. Since there are so many, I released my captured specimen as the cup seemed a bit cruel.

Giving this situation some thought, it occurred to me that lately I've noticed the coraline on my glass has been peeling off here and there like old paint. Looking at the starfish, they are all on coraline (and none near coral or in the sand that I saw), I suspect the coraline is their food source.

I will post pictures once we find the camera lost in the chaos we call Christmas decorating.

Has anyone seen or heard of a similar thing??