The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric cornutes and mitrates.

However, multiple lines of evidence argue against the calcichordate hypothesis, and stylophorans are now widely agreed to belong to the echinoderm total group.

In the calcichordate hypothesis proposed by Richard Jeffries, it was suggested that some or all stylophorans might have had gill slits like chordates, and the appendage was a tail that contained a notochord.

[6] Scanning electron microscopy of preserved soft tissues in the single appendage of two genera of stylophorans showed the appendage contained an ambulacral canal with tube feet covered by mobile plates, and was not a tail or stalk with fixed plates covering a notochord or neural tube.

Stylophorans are therefore reconstructed as true echinoderms of uncertain affiliations, without radial symmetry but with stereom and a water vascular system.

Rather than swimming with a muscular post-anal tail as in chordates, mobile genera would have crawled "arm-first" using a water vascular system, like starfish and sea cucumbers.