Each of the members of slipknot have or have had their own side projects, the original idea was to get some of the best musicians and create one band. Stone sour is one of the side projects.Plus, if I recall, most of Slipknot re-formed to become Stone Sour.
My gf's family has hookups with the lead singer of Mudvayne, he grew up about twenty miles from where I live, and that is where most of her family lives. One of her brother in law's was in a band that toured with Mudvayne, its name was V-shape mind.
Her sisters boyfriend was stage manager, and he also has met slipknot without their masks on and stuff..Im not that into them, but damn, that is impressive!
Anyway, thats who I heard it from