Stensioella heintzi is an enigmatic placoderm of arcane affinity.

Stensioella heintzi has an elongated body, a whip-like tail, and long, wing-like pectoral fins.

Like the sympatric Gemuendina, S. heintzi had armor made up of a complex mosaic of small, scale-like tubercles.

Despite this detail, coupled with superficial similarities in skull plates, and gross, superficial similarities between its tubercles, and the tubercles of the rhenanids, some paleontologists believe that there are very few concrete reasons for S. heintzi's placement in Placodermi.

However, if this is true, then the holocephalids (chimaeras, iniopterygians, petalodonts, et al.) diverged from sharks before the Chondrichthyan Devonian radiation.