Caption and image courtesy of the Snowball Earth Web site: Early animal diversity (Knoll & Carroll, 1999) and phylogenetic sequence (blue lines) with divergence times calculated from an invertebrate-calibrated molecular-sequence analysis of extant organisms (Peterson & Butterfield, 2005). The “plankton explosion” refers to a marked increase in size, diversity, ornamentation and turnover rate among eukaryotic plankton (acanthomorphic acritarchs), which is tentatively attributed to predation by eumetazoa.