That's good, jan. I'm going to modify it slightly and throw some mulm into the mix:
Detritus - Organic matter derived from dead or decaying plants and animals and their waste products (e.g., skin cells, feces, etc.). Serves as a food source for certain aquatic and terrestrial animals (see [Tank Critters article]) and as a substrate for bacterial and fungal growth.
Mulm - The end-product of fully decomposed [detritus] in an aquarium. Appears as brown debris, usually under gravel.