Category Questions

Abundant acritarch fossils, some giant-sized by micro-standards, are thought to be fossil cysts or other life stages of algae. Although we cannot discern exactly "who" they are, they speak to us of life's diversity over millions of years.

Categories are maps, but maps are not the territory. In the game Twenty Questions, the basic categories of animal, vegetable, and mineral underestimate the richness of life-forms. Similarly, basic categories such as "small," "large," "single-celled," and "multi-cellular" can confuse us.

Mid-right and bottom: Photos of ancient filamentous microfossils; the one above and the one to the right are fossil cyanobacteria. (Photography by Gonzalo Vidal, mid-right, and bottom)