Stingrays

A ray is essentially a flattened shark — same cartilage skeleton, same gill slits, with the mouth and gills tucked underneath and the eyes on top. They fly rather than swim, rippling the edges of those wings to move, and spend much of the day half-buried in sand with only their eyes showing. The barb is defensive and only used when a ray is stepped on or cornered; the ones in the touch pool have theirs trimmed, the same way you'd clip a fingernail, so you can run two fingers flat along a wing as they pass.