Help ID these growing in sump

[stifflingspoon]

Can anybody help ID this sorry if it’s been answered, first post don’t know how to use site yet.
they are growing through sump and think have come from second hand chiller, that I thought I’d cleaned properly.

 

[Zach B]

These look like sponges/filter feeders to me, I also have them in my sump

 

[stifflingspoon]

These look like sponges/filter feeders to me, I also have them in my sump

Do you think it’s bad? I think they have been transported by a 2nd hand chiller

 

[Zach B]

No I think they are beneficial filter feeders. Unless someone else knows something about them...

 

[Zach B]

Usually appear in darker areas of the sump or tank, not bad as far as I know

 

[Sharkbait19]

Might be a hydroid, sponge is also a possibility.
They are common in new tanks and not at all harmful.