In a sink waste pipe, just after trap I found three objects too big to have fitted down the plug hole. They were oblong and about an inch and a half long (bit like a thumb) and were dark coloured and odourless. Sink wasn't backing up or anything, just happened to spot them. They looked solid, perfectly formed, but crumbled easily when touched to a sort of sandy, powdery substance. Washing machine and dish-washer connected to same waste. Any ideas?