I'm sorry, but those are all going to starve. A linkcia needs a tank that's over a hundred gallons and is very mature, and even then they'll most likely starve. A 55g isn't enough for even one.
They can last a good few months in a small tank, but they're gradually starving the entire time. Slow death for a beautiful animal.
They don't have much of a chance anywhere else, but nevertheless, you should remove them and hope someone with a large tank buys them. Also, if your LFS told you that was okay, they were lying to sell the starfish and they should not be trusted in future.