“Ninety-nine percent of all the plastic [that is supposed to be polluting the sea] is missing, [we do not know where it actually is]” oceanographer Erik van Sebille says on Unexplainable. “We have dark plastic. Like the astronomers have dark matter and dark energy, we oceanographers, we don’t have an idea where most of the plastic in our ocean is. We’ve lost it.”

Researchers like van Sebille want to know where the plastic is going so they can better understand its effects on marine life. What harm is this plastic causing to marine life, and can it be undone?