Symmorium is an extinct symmoriiform cartilaginous fish from the Devonian and Carboniferous of the United States (Illinois)[1][2] and Russia.

[3] The type species, Symmorium reniforme, was named by Edward Drinker Cope in 1893,[4] with other species assigned to the genus having since been reclassified into other genera such as Petalodus.

Symmorium bears close similarity in size and appearance to Stethacanthus[5] but lacks the "spine-brush complex" in place of the first dorsal fin.

[6] Some paleontologists think that the two forms represented the males and females of related species, while other scientists think they were distinct genera.

This article about a prehistoric cartilaginous fish is a stub.