The indoor I'm renting time in this winter has one of the new coated sand footings. It's a lovely cushion and I've been enjoying riding on it. One evening, I noticed something glittering and retrieved it - it was smoothish piece of glass about the diameter of a prince of wales spur tip. Since then, I keep finding them. Is this a by product of heat coating sand? Should I be worried? On a firm surface, I could see high potential for injury, but this footing is springy.