Biologists have finally revealed the mystery behind the origin strange eelgrass fairy rings growing off of Denmark's coast. These rings are often observed in the shallow waters of the Baltic Sea. Tourists in 2008 captured the images of these rings for the very first time and later, in 2011.

The topic has emerged out to be an interesting theme for debates in the geosciences world. Now, the biologists have uncovered the fact that these rings are made of green eelgrass and surrounds areas of dirt on the seabed where they grow. Width of these rings can reach up to 49 feet.

Earlier, there were assumptions that these rings might be leftovers from World War II bomb craters or might be the 'landing marks for aliens'. However, these assumptions have been proved wrong by Jens Borum from the University of Copenhagen and Marianne Holmer from the University of Southern Denmark.

Eelgrass is a flowering plant which grows in a radiating pattern, inform the two biologists working on the project. Presence of poisonous substance, sulfides, is responsible for the death of eelgrass.

The eelgrass traps the mud and the presence of sulfide in the mud is responsible for death the eelgrass. When the eelgrass starts dying, the middle area becomes empty first and leaves a hollow circle. Researchers are putting efforts to curb the disappearance of eelgrass as it is essential for the survival of aquatic life.

The growth of rings on land has been explained to be the outcome of a similar outward growth of fungi which can be seen in Namibia's desert grasslands. Some challenge the explanation as they think gas seeps, resource competition, termites, or possibly ants are responsible for the growth of these rings.

The revelation by the two biologists has been published in the journal LiveScience.