Anemonia viridis, the snakelocks anemone (family Actiniidae), is a photosymbiotic sea anemone abundantly distributed in rocky shallow waters of the northeastern Atlantic and Mediterranean Sea. Its long tentacles display a distinctive green or purple hue derived from endosymbiotic Symbiodiniaceae and host-encoded fluorescent proteins that protect against photoinhibition. The species is a classical model for studying cnidarian-algal symbiosis in temperate settings and has contributed significantly to understanding the molecular diversity of GFP-like chromoproteins in cnidarians. Genomic resources and transcriptomic studies reveal extensive immune and symbiosis-related gene expression.