Which organism in Shark Bay Australia is thought to be the largest in the world?

It sounds like the stuff of science fiction: Two closely related species hybridize and create a superorganism whose growth and expansion seems unstoppable. That’s what’s happened in Western Australia’s Shark Bay, researchers say, where a seagrass meadow stemming from a single hybrid plant has extended its reach across more than 180 kilometers—an area the size of Washington, D.C.

Two years ago, scientists discovered some of the seagrass there was a clone of a Poseidon’s ribbon weed ("Posidonia australis") that had 40 chromosomes instead of the typical 20. They think half those chromosomes may come from the ribbon weed and half from an unknown species.