Hoploparia westoni   CLASS - Malacostraca ORDER - Decapoda FAMILY - Nephropidae GENUS/SPECIES - Hoploparia westoni ROCK UNIT - Pierre Shale AGE - Upper Cretaceous (70 million years old) LOCALITY - Fort Peck, Montana, USA This marine "crayfish" was preserved inside of a carbonate concretion, a mass of minerals that filled in pore space of the sea floor muds. The hardening of the concretion was very early, because the crayfish was fossilized before it could be crushed by burial mud. PRI 42410