The Seedurns you came across are known as Demon Kin, beings that have been infected or possessed by demonic aura. The intensity of the infection can vary but it they still acted wild and untamed in actions then it would be that it was a second hand infection or the demons are still to weak to materialize in this world.
As I have mentions before this worries me as this means the demon race known as the Lunarines are soon to invade this dimension. I am greatly bothered by this as it is many years too early for their return. My defense against their return as not as strong as anticipated. Hopefully this invasion can be repealed before it is too late.