Phaeodactylum tricornutum

Diatoms, key photosynthetic micro-eukaryotes, found in all aquatic ecosystems are classified based on their symmetry into pennates (elongated) and centrics (radial symmetry). Phaeodactylum tricornutum is a marine pennate species that has become an experimental model used to understand diatom biology. The nuclear genome is chimeric, containing genes derived from ancestral endosymbioses with red and green algae, and enriched by genes acquired laterally from bacteria. Novel combinations of genes enable novel metabolisms (e.g., related to cell wall biogenesis).