These are the little odds and ends (quite literally) of trilobite parts. (From top left to right, then bottom left to right... what I think they are) This is the middle segment (the thorax) of a Flexicalymene meeki; on this rock there is a small tail (the pygidium) of a Tricopeta???; this from the head plate (the cephalon) of an Isotelus (middle Ordovician); this is a whole Flexicalymene meeki; again some more naughty bits (pygidium) of a Tricopeta...