I'm pretty sure most species of Rays have some kind of stingers or spines. Always shuffle your feet while fishing in the surf, especially if you don't wear boots.
Years ago... while surf fishing, I stepped on something soft and felt it squirmed under my foot. After the session, I found this Sting Ray barb sticking out of my wading boot. Another fraction of an inch and it would have gone all the way through and into my foot.