Spirulina: Is it an algae?

Spirulina (Arthrospira platensis) is a cyanobacterium, not a true alga. It's prokaryotic (no nucleus), closer to bacteria than to the eukaryotic microalgae (chlorella, Haematococcus) it's constantly compared with. This taxonomic distinction matters: cyanobacteria can produce microcystins (hepatotoxins), and contamination from co-occurring Microcystis species is a real quality concern that the "superfood algae" branding overlooks.Publications of interest:https://pmc.ncbi.nlm.nih.gov/articles/PMC10302721/https://pmc.ncbi.nlm.nih.gov/articles/PMC10221061/https://pmc.ncbi.nlm.nih.gov/articles/PMC5371831/