UREA IN DIATOMS? “One of the first surprises to emerge from the sequencing of diatom genomes was the presence of an apparently fully functional urea cycle. Diatoms were, in fact, the first photosynthetic organisms to contain all the genes for such a cycle…Prior to its discovery in diatoms, it was believed to have been a metazoan innovation.”
http://jxb.oxfordjournals.org/content/early/2012/01/20/jxb.err441.full