One day in February when Stuart and I were looking round the garden he spotted these strange lumps of jelly-like substance among the gravel on the path. I had noticed this once before then forgotten to check it out. I contacted Gwent Wildlife Trust as there is usually somebody knowledgeable there who can often put a name to anything. As usual someone did. It is called Nostoc pruniforme and is a form of cyanobacteria.
Cyanobacteria inhabit nearly all illuminated environments on Earth and play key roles in the carbon and nitrogen cycle of the biosphere. In general, cyanobacteria are able to utilize a variety of inorganic and organic sources of combined nitrogen, like nitrate, nitrite, ammonium, urea, or some amino acids. Several cyanobacterial strains are also capable of diazotrophic growth, an ability that may have been present in their last common ancestor in the Archaean. Nitrogen fixation by cyanobacteria in coral reefs can fix twice the amount of nitrogen than on land—around 1.8 kg of nitrogen is fixed per hectare per day. The colonial marine cyanobacterium Trichodesmium is thought to fix nitrogen on such a scale that it accounts for almost half of the nitrogen-fixation in marine systems on a global scale.