Weird thing in filter

[jpgnmt]

I had a bunch of these things in my Magnum filter that I use to move water through my sterilizer. They almost look like slugs. They were on both sides of the filter media. I think they appeared and multiplied quickly as I just noticed them and I keep an eye on the media to see when I need to clean it. Any thoughts?
Thanks in advance,
jpgnmt

 

[meowzer]

I believe they are sponges...I have lots of them in my sump, and also in my canisters

 

[ophiura]

Yup, they are Q-tip sponges.
Often common in young tanks and a sign of a possible nutrient problem as they "bloom" and then die off in most cases. If you do not have a new tank, you may just want to reassess stocking/feeding. Not a problematic organism but definitely, IMO, a useful indicator organism.

 

[jpgnmt]

Thanks for the info, meaning too much feeding, too many fish, tank is 20 months old.