Researchers describe the locations, nine on the coast and six inland, as the unsung heroes of the natural world, The Times of London reported Wednesday.

Britain's waters contain about 10 percent of the world's 35,000 species of algae, which are among the most important life forms on Earth.

"Algae are more than just green slime," said Julie Brodie of London's Natural History Museum. "They are fundamental to the environment."

Brodie said scientists believe algae have been around in one form or another for more than 1 billion years.

Among the 15 locations listed is a freshwater area in Cornwall near St. Just that has 100 species of algae, two of which are classified as rare. Another important area is a coastal site at Lundy Island off Devon with 300 species of algae.

The 15 important locations are listed in a report published by the British Phycological Society and the Natural History Museum.