Pioche Shale Fm.
Rachel (near area 51), Lincoln County
Cambrian Oncolite sp. algal ball stromatolite like
size: 27 cm x 8 cm witha natural side
preparator: Gianpaolo Di Silvestro
"Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by cyanobacterial growth. Oncolites are very similar to stromatolites, but, instead of forming columns, they form approximately spherical structures