This species of rock can exhibit many forms and colors. It may be a fossil or sedimentary formation in a shallow water environment. This particular variety is also known as Kambaba Jasper. It is a deep green with orbicular structures.
If fossil, the rock is comprised of colonial structures created by Cyanobacteria, and are among the oldest fossils on earth dating back some 3 billion years when simple cell lifeforms first appeared. Stromatolites are now found in only a few places. I found this piece at a rock shop in Orderville, Utah but the clerk didn't know of its origin.