Vice, of all publications, examines the strange chemistry of the first-known psychedelic sponges… trying to figure out why sponges would make something as potent as DMT anyway:
It would be a tragically anthropocentric mistake to assume that Smenospongia aurea produces 5-Br-DMT and related tryptamines to provide terrestrial vertebrates such as you and me with a transient psychedelic high. Serotonin is present in nearly every living organism, yet appears to be conspicuously absent from the Porifera, having only been detected on a handful of occasions in the history of sponge analysis. Let me propose a simple explanation: Serotonin is an extraordinarily potent barnacle attractant. So potent a barnacle attractant is serotonin that it’s used as the gold standard in the Kawahara barnacle-settlement assay.
…
But what’s more important than the lack of serotonin in sponges is the abundance of close serotonin derivatives. In the same manner that serotonin induces barnacle settlement, drugs that modify serotonin neurotransmission, specifically SSRIs like the pharmaceutical antidepressant imipramine, act as potent biocides repelling barnacles and other would-be colonizers.
…
In an ocean dangerously polluted with antifouling biocides like tributyltin, a future in which boats are painted with the psychedelic essence of Smenospongia aurea is an uplifting prospect.