As they say, one man's trash... Rotti is the bits and pieces of smalti left over when the smalti pizzas are cut into tesserae. Very irregular pieces, small and large chunks, slivers, and the rounded edge pieces. It makes great filler, and many artists enjoy the strange variety of shapes and colors. Sold in 1lb. increments in the mixed colors only. Limit of 4 lbs per order.