In its natural environment, seaweed plays a major role in marine ecosystems. Not only does the plant provide nutrients and energy for organisms up the food chain, but these plants also provide shelter and habitat for many different species. So when 70 kilometers of seaweed vanished from the Australian Coast in the 1970s and 1980s due to high levels of sewage, we would expect to see some dramatic environmental problems. But thanks to recent recovery efforts, a habitat-forming species known as crayweed is making a successful comeback in Sydney’s coastal waters.