What is this?

[HawkeyeDJ]

Found many of these in my AIO filter for the first time today during a water change. Tank is 3 months old. 24 gallon cube. FOWLR only ATT.

These are generally the size of an apple seed.

Can you tell me what they are? Should I be concerned?

 

[JGT]

Pineapple sponges, harmless.

 

[HawkeyeDJ]

Pineapple sponges, harmless.

Thank you.