Lemmasts

Lemmasts are a fictional taxon used in speculative biology and fantasy settings to describe a class of drift-form, gelatinous colonies that inhabit freshwater environments. In most depictions they form translucent, buoyant mats or spheres that slowly drift near the water’s surface, often exhibiting faint bioluminescence at night.

Morphology is variable by author but commonly features a multi-layered, jelly-like outer matrix enclosing a network of interconnected cells or filaments. The colonies may appear translucent or pale, with a central cavity that can expand during growth. Some portrayals describe a micro- to mesoscopic scale, with individuals ranging from a few centimeters to several decimeters in diameter. Photosynthetic cells or symbiotic algae are frequently depicted within the matrix, contributing to the colony’s energy budget.

Reproduction and life cycle are usually asexual. Lemmasts are said to propagate by budding or fragmentation: small fragments can detach and grow into new colonies, while certain mature colonies release dormant spores or cysts that germinate under favorable light and nutrient conditions. Seasonal blooms may occur in response to nutrient influx or temperature changes.

Ecology and habitat place lemmasts in temperate to cool freshwater systems, including lakes, slow-moving rivers, and brackish interfaces in some settings. They are described as primary producers or as part of a microbial-ecology web, providing habitat and shelter for microinvertebrates and acting as a food source for certain small fish or invertebrates in fictional ecosystems.

Etymology and usage note that the term combines imagined roots for “lem” and “mast,” intended to evoke a creeping, colonial organism. In fiction, lemmasts often influence water clarity, nutrient cycling, and the dynamics of fictional aquatic communities.