(CNN)A record-breaking mass of smelly seaweed stretching from West Africa to the Gulf of Mexico has been identified using satellite imagery.
The seaweed bloom, called the great Atlantic Sargassum belt, is the largest ever of its kind, according to a new study.
Researchers at the University of Southern Florida used satellite imagery to determine that the giant floating mass of seaweed is a whopping 8,850 kilometers (5,000 miles) long. It weighs an estimated 20 million metric tons, or the equivalent of 1.6 million double-decker buses.
Scientists first noticed that seaweed was spreading rapidly across the Atlantic and growing in mass in 2011.
"There's a huge amount of Sargassum in a place where it's never been seen before," said Mengqiu Wang, co-author of the study, which was published in the journal Science.
Wang said the seaweed was of "great ecological value" to marine life such as fish, crabs, shrimps and turtles that use it as a habitat or food source.
But excesses of Sargassum like the recent explosion cause some problems for marine life, as dead Sargassum sinks to the ocean floor and can "smother corals and seagrasses", according to the university's press release.