Basemekanic

The Basemekanic are vast Xenos beasts, that have thick metallic hides. Several of the creatures invaded and subjugated Gamma-Incunablar during the Great Crusade, but they were later destroyed by the Third Legion and the 43rd Veradan Solar Auxilia.^[1]

Source

• 1: The Horus Heresy Book Nine - Crusade, pg. 205