

They adore the object
Thank you guys for your help!! Fried rice and friends are doing great in their new home in my workplace. They got right to work on all the algae. And I set up their sponge filter.
Since this tank used to belong to a fish and I have not used big fish tanks very much before, there’s some equipment in there, and I don’t know what it does.
The shrimp particularly seemed to like this object that I have a picture of here. It seems to be on a timer and circulates water around. I was worried that it might suck them in and so I turned it off. Then I came back to see like 3 of them standing on it eating so I don’t necessarily want to take it out. The little pieces of plant the shrimp came with kind of got stuck in it somehow but none of the shrimp seemed to have.
Does anybody know what it is? Or the other thing that’s also in the second picture for that matter? Thanks again for all your help.
Bonus picture of orange shrimp on rock. I think the dark spots are her ovaries but I’m unsure.