This is a picture of weathered fossiliferous limestone of the Pitkin Formation. It was taken in a quarry near Batesville Arkansas. The picture displays fossil remains of two common aquatic animals that lived in the shallow sea covering northern Arkansas between 360 – 320 million years ago.
The screw-shaped remains are parts of bryzoans; they are commonly referred to as Archimedes screws. The nut-shaped fossils- which also resemble rolls of smarties candies- are the remains of crinoids, commonly called sea-lilies, which have living relatives in the ocean today. Both animals lived by attaching themselves to the sea floor and filtering food, such as plankton, from the ocean water.