Peter Ward of Yorkshire Water with the fossiled fern (photo: The Star. 26 Jan 05)

An unusual fossil was unearthed by contractors working on Totley's sewers in January 2005.

Initially they where baffled when their spades struck something solid and cylindrical in the soil beneath Aldam Road. Further investigation revealed a number of giant "tentacles" in the site where a new detention tank is being installed to reduce the risk of flooding in the area. A section of what the crew christened Ollie The Octopus was subsequently removed and the British Geological Survey consulted on the mystery.

Once experts had examined the evidence, it was established that, rather than a sea-going mollusc, Ollie was a section of root from a plant which grew in the prehistoric equivalent of the mangrove swamps found today around the Amazon or Northern Australia. The plant may have been as high as 150ft as the root still extends 60m underground - and probably remains in the same shape in which it grew millions of years ago before the plant died and was covered by mud.

The fossilised evidence suggests that during the Carboniferous period around 280 to 300 million years ago, Totley was at the heart of a tropical, swampy delta with soft ground ideal for giant ferns - one of the earliest forms of tree to evolve on the planet. Most will have been crushed and carbonised over the millennia to become the coal so important to Yorkshire's heritage. However, examples are found occasionally where the land was once much sandier - such as on the banks of a fast-flowing river or on a beach - and are therefore less likely to alter their composition under the pressure of overlying rock strata.

The contractors team have won a coveted Five-Star Award for the work in Totley and made many friends among the community while improving the local sewerage network. It was a bonus for each of them to be left with a section of Ollie, a unique example of Yorkshire's natural history.