FOSSILS discovered on the Co Wexford coast have encouraged scientists to question some of their ideas about life on earth more than 500 million years ago.
The jellyfish like fossils, which are 510 million years old, were preserved in rocks from the Upper Cambrian period.
They support the idea that a unique - and now extinct - group of creatures which superficially resembled today's jellyfish, lived in the seas.
Until now, it was thought these early jellyfish like creatures died out around 560 million years ago, but the Wexford fossils appear to have survived for another 50 million years - probably by moving into deep water. There, they would have been able to avoid competition and predation by newly evolved and more complex animals.
The fossils, named Ediacaria booleyi and Nimbia occlusa, were taken from rocks near Duncannon by Dr Alan Insole of Bristol University. Dr Insole said he was amazed to see rock surfaces shaped like jellyfish.
When he pointed them out to his colleagues "they just fell about laughing and wouldn't believe me", he said. But one of them Prof Brian Williams, did believe him and together they wrote a description of the find.
They sent it to Prof Peter Crimes of Liverpool University, an international expert on this type of fossil.
He was so excited that he travelled immediately to Wexford to examine the find.
The umbrella shaped fossils are mostly about five centimetres wide, but their shapes are clearly delineated in the sandstone.
Just how they came to be preserved in this way is a crucial aspect of the research, since no similar fossil jellyfish has been found in younger rocks.
Although the fossils were discovered in 1988, it has taken some time to complete and publish the results of research prepared by a team assembled to assess the find.
The scientists argue that these Ediacarans must have been much tougher than today's jellyfish. Nor are certain features of true jellyfish, such as the mouth and stomach, found in these Ediacaran "jellyfish".
Professor Crimes suggested "they were an early evolutionary experiment at making an animal that ultimately failed."
The search now continues to see how far back in time these creatures extended.