Thorn Beasts are used as food by the Covenant, and Jiralhanae in particular. They appear to be docile herd animals, and may have been domesticated for consumption. Their neck and head contain high concentrations of neurotoxins, likely a defensive adaptation against predators that go for the head or neck to kill. While they are found on planets other than Doisac, their popularity among Jiralhanae may show that they inhabit a variety of worlds, perhaps transplanted there by the Forerunners' after the Halo Array activated.