Just went to put ds in the bath (i shower so dont use the bath a great deal) , in the centre of the bath on the side is a mound of fluff, it is dark blue or black and is definitley what he picks out of his belly button when he has had a bath and then wipes on the side. He has blatantly collected a weeks worth here and not disposed of it. It has grossed me out slightly. AIBU to add it to his coffee later?