This stromatolite represents one of Earth's most enduring life forms. Each layer captures countless generations of cyanobacteria, tiny organisms that trapped sediment and minerals as they grew. Over millions of years, these bacterial mats built up into the layered, mound-like structure you see here. The bands of color record changing environmental conditions in the shallow seas that once covered Bolivia.

Sixty-six million years ago, during the final age of the dinosaurs, these microbial reefs thrived in warm Cretaceous waters. Stromatolites like this one are living fossils in the truest sense. Their ancestors built the first reefs on Earth over 3.5 billion years ago, long before plants, animals, or even complex cells existed. The bacteria that created this specimen used the same reef-building process that has shaped our planet's oceans for billions of years.