"Adria birthed these golems from the Blood Marsh. Their bodies were formed from the water and earth of the marsh itself, while the venom of the marsh creatures gave them life. Their very skin seems to burst with the poison of this land."— Lorath Nahr(src)
Flesh Hurlers are the rarest, weakest and slowest type of Flesh Golem, but their ranged attacks are the most damaging of all of them, dealing very high Poison damage. They cannot be resurrected by Flesh Shamans.
Originally, the Flesh Hurlers were of pale color, as opposed to their released blood red appearance.