As I know that Sas's father keeps freshwater stingrays, I was not as perturbed by this message as I otherwise might have been, so I asked for further details.
She wrote back with the following picture, and this message: "The larger one is the female's (which she shed today) and the smaller one beside is the male's from a month ago".
I didn't even know that stingrays shed their stings and said so. She replied:
"They shed in order to grow new ones.. Just like sharks with their teeth"
I was completely intrigued by this stage, and she wrote me the following little essay:
Unlike a wasp stinger, a stingray stinger is not hollow and does not inject anything. It is simply a physical weapon, like a dagger, not a chemical one. Stingrays have a set of barbs each one smaller than the next. As one is used the next one in line grows to replace it. Very similar to the way sharks replace lost teeth. Stingray skin is covered partially in dermal denticles (literally ‘skin teeth’) that contain dentine just like normal teeth. They look like short pointed spikes when viewed under a microscope. The ray’s tail spines are modified dermal denticles that have become elongated so that the can be used as defensive weapons.
So if you zoom in on the picture you can see it looks very similar to a shark tooth...
And she signed off with a picture of her Dad's rays. What a nice way to brighten up the last evening of my 54th year!