Stromatolite
Girvanella sp
Algal Oncolites
Cambrian
Chambless Limestone
Marble Mountains, California
Oncolites are a very similar species to stromatolites. They form spherical structures instead of forming columns. They would form around a center point, such as a shell fragment.
4 1/8 inch x 3.5
Gehard G.H. Muehle collection