Yep. Have found them in the shoulders or right under the skin on the other side of deer we have shot.The soft bone makes it splinter like that. Why it would be at a school though does not make sense .
I know you've heard of Show and Tell at school. I found a 100 yr old token from a sawmill laying together with a French 2 franc coin from 1943. I know one kid got his butt paddled if his parents even knew he brought them to school.