WASHINGTON (AP) — What may be the oldest complete fossil on Earth paints a smelly but colorful picture of our microbial ancestors from nearly 3.5 billion years ago.

The fossil is the remains of what once was a purple-and-green slimy, smelly mat of single cell microbes that worked, lived and even communicated together in what is an awful lot like a prehistoric microscopic society. Nora Noffke of Old Dominion University in Virginia found the remnants of this life in sandstone rock in western Australia.