Bought a piece of live rock, found 4-5 small sea stars hidden in the rock

I purchased a piece of live rock covered in coralline algae to kickstart my cycle and when I came home after careful inspection I found at leat 4 -5 tiny sea stars in all the nooks and crannies. They look like brittle stars but I'm not sure. What should I do? Are the harmful for my new tank? Is my non-cycled tank harmful to them??

I uploaded a video on Youtube:

https://youtu.be/AxPna9SaF1A