Question about curveballs?

i was out with my friend tossing baseball and I decided to throw a knuckle curve completely side arm and noticed that it had really good movement early on and looked pretty confusing. Why is this and the other thing is i threw a different curveball overhand but rather than using traditional grip i pointed the horseshoe away from my throwing arm and placed my middle and index finger over the top of the horse shoe and thumb a little under the middle of the ball where the seams are the closest to each other and threw it like a curveball and it had good break to it. Does anyone know what this pitch is called or if I somehow found something new?