Back in August, I began a small science experiment. I buried five different objects in the ground outside my classroom, with the intention of digging them up at the end of the school year. Now, we can put our knowledge of waste and litter to the test. A Styrofoam lunch tray. A plastic grocery bag. A water bottle. A piece of paper. An apple core. What followed would be a test of evolution-meets-environmental-science. Which objects would decompose? Which objects would the microorganisms in the soil even recognize?

Today, when we dug them up, the lessons that we learned last Thursday were confirmed. The objects made from natural materials (the piece of paper and the apple core) were almost totally decomposed. All that was left behind was the sticker on the apple. That’s because organisms like worms, fungi, and bacteria have all evolved alongside these materials; they recognize them, they eat them, and they can digest them.

But plastic and Styrofoam are a different story. The lunch tray, the grocery bag, and the water bottle were all still fully intact. They are made of strong, lightweight materials. And as such, they can remain in the ground for hundreds of years, because no organisms have yet evolved to break them down. So the next time you are tempted to use a Styrofoam lunch tray, think twice. That tray will still be polluting the Earth when you and I are dead and buried.