Brief communication - Phaeodactylum tricornutum is a bona fide calcifying diatom

Abstract Phaeodactylum tricornutum is an unusual member of the clade of diatoms, eukaryotic marine brown algae that possess a distinct cell wall made of silica. Phaeodactylum is a rare exception in diatom biology in that it does not require silica throughout its whole life cycle. Here, we demonstrate that Phaeodactylum has a calcifying activity, which is highly unusual in unicellular eukaryotes.