A kitten investigates glass milk bottles.

Glass isn't made from fossil fuels -- it's made from sand. Right, kitty?

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Once upon a time, both moms and milkmen filled glass bottles with milk. Now look around your kitchen and you'll probably see many plastics -- water bottles, soda bottles, food storage containers. Times have changed.

Sometimes going back in time is a good thing. Unlike plastic, which often is derived from fossil fuels, glass is made from sand. This renewable resource doesn't contain chemicals that can leach into your food or body. And it's easily recycled -- whether you throw bottles in your recycling bin to be turned into new bottles or reuse glass jars for storing leftovers. Sure, glass may break if dropped, but it won't melt in your microwave.