Sarcodactylis

Sarcodactylis is a fictional genus of marine invertebrates commonly encountered in speculative biology and science fiction contexts. The name derives from Greek sarx, flesh, and daktylos, finger, in reference to its proposed finger-like appendages that extend from a central body disk.

Members are described as soft-bodied, with a central disk-shaped body from which multiple slender, flexible podia radiate. The podia bear suction-like tips used for locomotion, feeding, and environmental interaction. In example depictions, individuals range from about five to twenty-five centimeters in diameter, and coloration varies from iridescent blue-green to mottled brown.

Taxonomy and relationships: Because Sarcodactylis is a fictional taxon, its systematic placement varies by author. Some speculative schemes place it near echinoderms because of radial symmetry and a water-vascular–like system, while others position it in an independent lineage within speculative deuterostomes.

Ecology and life cycle: In most portrayals, Sarcodactylis inhabits shallow marine sediments and uses its podia to probe the surrounding water for detritus and small organisms. It is typically depicted as sessile or slow-moving, with a free-swimming larval stage. Reproduction is usually described as sexual with external fertilization; some variants show short brooding periods for early development.

In culture and usage: The taxon is widely used in worldbuilding as an example of a soft-bodied echinoderm-like organism, illustrating how finger-like appendages could support feeding and locomotion in a sedimentary habitat. There is no real fossil record for Sarcodactylis, and its existence remains fictional.