Nature's diversity is unparalleled...shapes, sizes, colors, properties. These infinite unique properties sustain ecological cycles. Different animals and trees have different lifespan. For non living components also, some compounds are known to be extremely unstable, they decompose/degrade or react with other compounds very easily. And on the other hand, some other compounds are known for their stability. But whatever it is, whether it is a biotic or abiotic component of nature, everything has a predefined shelf life. Long or short, everything has an expiration date and beyond that, it will be converted into another component, entering the circle of life again in infinite layers.
But some man made items defy this natural cycle, like plastic. Plastic may take hundreds to thousands of years to decompose and enter the circle of life again. This is an anomaly, an error in the otherwise perfect process. When something with no expiration date in near future is produced at an alarmingly fast rate, it breaks the holy circle of life. Sooner or later it will take over the whole planet, and the damage will be irreversible. Even the mighty nature cannot fix this anomaly.