today, i was giving a surf lesson, and i was standing in about stomach high water. all of the sudden something hit my left calf, hard. i then immediatly asked the kid to whom i was giving a lesson if he kicked me, since that it felt like someone kicked me, but he said no. then again the thing rammed into the same spot it did earlier. i now have a bruise and weird lines on my calf. i'm pretty sure its not a skate because the "attack, or run-in" seemed to hard and powerful. i think it was either a rather large fish, or maybe a sand shark. any suggestions? their were a lot of dolphins out, haha but im pretty sure i would know it was one.