The Oldest Proposed Cell Microfossils Come from Structures Called _____

Question

The oldest proposed cell microfossils come from structures called _____.  
A) stromatolites
B) crystal filaments
C) hydrothermal vents
D) pyrite
E) tectonic plates

Accepted Answer

Stromatolites are layered structures formed by the trapping, binding, and cementation of sedimentary grains by microbial communities, including some of the earliest known life forms on Earth. Within stromatolites, proposed cell microfossils have been identified and dated to as early as 3.5 billion years ago. Crystal filaments, hydrothermal vents, and pyrite have also been associated with early life on Earth, but stromatolites are the best choice for this question. Tectonic plates are not relevant to the topic of cell microfossils.