image: This 570 million-year-old fossil (the large gray structure in the middle) is no larger than a sand grain, but X-ray microtomography shows clearly the cells and cell nuclei (represented by the yellow shapes). The fossil resembles an animal embryo, but is thought to represent an encapsulated unicellular organism in the process of producing spores. The backdrop shows the phosphoritic rock in which it is found--each little round grain is a fossil! This image relates to a paper that appeared in the Dec. 23, 2011, issue of Science, published by AAAS. The paper, by T. Huldtgren at the Swedish Museum of Natural History in Stockholm, Sweden, and colleagues, was titled, “Fossilized Nuclei and Germination Structures Identify Ediacaran “Animal Embryos.” view more
Credit: Source: Swedish Museum of Natural History