Beach sand is kinda play sand, or is that regular sand that people can play with? Which makes it play sand again, but it was from the beach. Regular sand might be what's in an hourglass, but if you were playing while the hourglass was operating, does that make it play sand at that point? Dizzyingly, Which sand IS the correct sand for playing in, or time keeping, or just regular?
Seemingly a deeper subject than one might suppose.