Many scientists now believe photosynthesising life on earth could date back more than 3.5 Billion years. One form of life present at this time would surely have been cyanobacteria. At this time the atmosphere would likely have been a mix of Nitrogen, Carbon Dioxide and Water Vapour (no oxygen at that point). However cyanobacteria, as a waste product, just like the photosynthesising plants that would later come to dominate the planet, produced oxygen. This was a game changer, albeit a slow one, as cell by cell, colony by colony, these types of organism puffed O2 into the atmosphere over billions of years, which eventually facilitated the wide variety of life forms we see today.
Of course between now and then many species have come and gone but one resilient form of life has remained little changed in over 3 billion years, and its now living on our garden steps! Welcome to the garden Nostoc, most likely Nostoc commune, although there are many different species.
This photosynthesising, nitrogen fixing, precambrian ‘Blob’ is one tough cookie. Not only as a species has it survived the Eons, as individuals these things can be sunburnt, frozen, soaked and repeat, over and again and they just keep on going. We have witnessed this ourselves this year on our garden steps as these small colonies of cyanobacteria became totally desiccated and turn into brown scaly lumps, only to quickly swell again when the rains return.
There is a fair amount of information about Nostoc online, including some of the odd and not so odd names it goes by, such as Mares Eggs or Witches Jelly. Some people believe it came from outer space (by the way, it reminds me of the movie The Green Slime from the 1960’s). Other people eat it. But we are just glad it’s here.