For most of the long nineteenth century, the apparently hybrid biological workings and the unstable taxonomical status of moulds and fungi puzzled and fascinated scientists. Their ubiquity, plasticity, and position in what Ernst Haeckel termed a ‘boundary kingdom’ made moulds and fungi ideal imaginative substances for weird horror writers like William Hope Hodgson in the 1900s: they are ecoGothic organisms par excellence (abject, necrophagous, evasive, transmutable, transgressive, adaptable, numerous). Hodgson’s fungal monsters populate liminal marine spaces - islets, derelicts, shores, and coasts – borderland locations within which it was easy to conceive the emergence of strange new forms of life. Haeckel’s ecological concept of the ‘boundary kingdom’ can function on multiple levels, describing the intermediate space between animal and vegetable, land and sea, dead and alive, human and other. Hodgson’s weird sea stories ‘The Derelict’ and ‘The Voice in the Night’ work to collapse such binaries and hierarchies by addressing the anxieties triggered by the interstitial qualities and scientific uncertainty of mycological and mycetozoan organisms. The border zones represented by shorelines and wrecked or abandoned ship become alternative ecological sites in which moulds and fungi (often seen as evolutionary dead ends) can evolve anew into frightening but more advanced forms, challenging preconceptions about the nature of life and elevating the status of mould and fungus in the natural world to equal that of animals and plants.