An ancient algae first spotted four decades ago will now join the collection of the Natural History Museum.

The Great Barrier Reef might be the world's most famous underwater ecosystem, but hidden in UK waters lies an ancient marine world you may not have heard of. Known as maerl beds, these carpets of coral-like seaweed create some of the richest habitats in the sea. And 40 years ago, while studying one such bed for her PhD, Prof Christine Maggs found a fragment of pink-striped seaweed living on maerl she had never seen before. The discovery would become a lifelong obsession and a decades-long scientific puzzle. Maerl beds may closely resemble corals but they are in fact thousands of pieces of free-living calcified seaweed that can interlock to create a carpet brimming with life. Hours of trawling through the literature seemed to confirm that no-one else had known what this little seaweed that lived on maerl was either. Prof Maggs suspected it was a new species to science. She continued the hunt after her PhD, and the tiny seaweed would accompany her throughout her career, with fleeting glimpses including once on an underwater animal called a sea squirt, although never enough material to pin its identity down. The Natural History Museum collection of seaweed pressings which the new species has joined