what is the BROWN matter in the sponge filter

[summbrz]

when i wash a cycled sponge filter, i can see the Brown matter
does the Brown matter nitrobacteria or the wastes

[warblad79]

Combination of poop and food that accumulated

[DC Discus]

Commonly referred to as 'detritus'. Bacteria produce wastes too.
Cheers,
DC