Hydroid? Bad?

[Euphylliaphyle]

I found this inside my canister filter. I think it's a Hydroid. I've heard bad things about them, but I'll put the question to R2R denizens.
Even if bad, does it make a difference that it is in the canister filter? I figure it's best there, you know, filtering. Thoughts?

 

[KrisReef]

That looks like a bleached bubble tip anemone, or a glass anemone. Having either in the filter isn't going to help with filtration. If it is a glass anemone, you want to remove it from the system asap. They tend to spread, as Aiptasia tend to bother corals and have caused issues for many tanks.

 

[PolypPocket]

Almost looks like the kind of anemone Pom Pom crabs use to cheerlead.