jahSepp was a sentient and sophisticated multi-dimensional eukaryotic organism.
They claimed to have been living harmoniously until their ecosystem started to be irreparably damaged by what they believed was Starfleet utilization of spore drive. One member of the species broke through the confines of the Mycelial network at great personal risk, and managed to reach Sylvia Tilly. In her, she found the memory of May Ahearn, and started using it to manipulate her. (DIS: "An Obol for Charon")