mereterminids

Mereterminids are a hypothetical group of organisms characterized by a unique dual life cycle. The term itself is a portmanteau of "meromictic" and "thermid," suggesting a connection to stratified lakes and thermal conditions. The core concept of mereterminids involves a sessile, multicellular stage that lives within the permanently anoxic, saline monimolimnion of a meromictic lake. This benthic stage is theorized to be a highly specialized filter feeder, deriving nutrients from the chemical gradients and dissolved organic matter present in this extreme environment.

The second phase of the mereterminid life cycle is a planktonic, often motile, form that inhabits the upper, oxygenated layers of the lake, the mixolimnion. This pelagic stage is believed to be responsible for reproduction and dispersal. The transition between these two forms is the most speculative aspect of mereterminid biology, possibly involving a complex hormonal or environmental trigger. Due to their presumed habitat in deep, inaccessible lake layers, direct observation and study of mereterminids remain highly challenging, placing them firmly in the realm of theoretical biology and speculative ecology. Their existence, if proven, would represent a significant adaptation to some of Earth's most unusual aquatic ecosystems.