What are these guys doing?

[Mark Novack]

Is this how they procreate? The stars, they've been doing this for several days.

 

[Silver14SS]

Google search says it might be pseudocopulation. Looks like stars either broadcast spawn or grow from pieces of an existing star.

https://en.wikipedia.org/wiki/Brittle_star
"Fertilisation is external in most species, with the gametes being shed into the surrounding water through the bursal sacs."

 

[Mark Novack]

Well, whatever was going on is completed. 5 days they stayed together. Maybe I'll be a grandpa?

 

[Mark Novack]

Nope, it was an illusion. They are still locked together. They are supposed to concentrate on cleaning, not whatever they are doing. Bad Astropecten. Bad stars.