A few months ago, a person walking along a Canadian beach made a stunning discovery: what appears to be a yogurt container from 1976, in generally good condition.

A photo of the container — which features an Olympics logo from the summer games held in Montreal, Quebec that year — went viral on social media, serving as a reminder of the growing issue of plastic pollution in oceans around the world. Plastics can take centuries to degrade, harming marine life until they do.

The discoverer who happened upon the Yoplait cup acknowledged that this particular piece of plastic seems to be in better condition than it ought to be, given its age. He speculated that "it perhaps came from a dump site more recently and had been sheltered from the elements for much of the last 40 years," CTV News Montreal reported.

This image shows where plastics are concentrated in the ocean.

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Researchers have found that the lifespan of discarded plastics range from decades (for lighter items such as plastic bags) to hundreds of years. Indeed, it takes about 450 years on average for a plastic bottle to degrade, according to research from the New Hampshire Department of Environmental Science. And because the ocean has a lower temperature and less oxygen than land, plastics that get caught there take even longer to break down.

Even after the plastic breaks down, though, the issue doesn't necessarily go away. Tiny fragments of degraded plastic items, not always visible from the surface, can become toxic over time and continue to contaminate ocean water, which can be swallowed by marine life.

In a January 2016 report published by the World Economic Forum, researchers estimated that by 2050 there will be more plastic than fish in the world's oceans, based on weight. Each year, the ocean takes in about eight million tons of plastic, CNN reported.