Researchers have found microplastics less than 300 m in size in coral skeletons. The team developed a new protocol to extract and detect microplastics and applied it to coral samples from the Gulf of Thailand. The finding may also explain the 'missing plastic problem,' where about 70% of plastic in the oceans cannot be found. The corals may act as a 'sink' for microplastics, absorbing them from the marine environment.