deltoeids

Deltoeids are a term used in speculative biology and science fiction to describe a hypothetical lineage of aquatic-terrestrial organisms characterized by deltoid-shaped appendages. The term is not used in mainstream biology and has no confirmed real-world counterparts.

Etymology and classification: Derived from the Greek delta for triangular shape, combined with the -eids suffix used in taxonomic group names. In most fictional taxonomies, Deltoeids are placed in a parallel clade to known arthropod lineages, with an origin from a panthalassian supercontinent; specifics vary by author.

Morphology and ecology: Deltoeids are described as having triangular, flat plates along the body and four to six limb-like projections. They occupy coastal, brackish habitats in speculative worlds, scavenging microfauna and algae; some depictions assign photosynthetic tissue to the plates, others do not. They reproduce via external spawning or brood care depending on setting.

Cultural presence and reception: In fiction, deltoeids are used to explore themes of convergent evolution and alien archaeologies. Critics note they are an example of world-building device rather than a real taxon; no consensus on their real-world validity exists.