An unexpected find has sparked interest throughout the community.

Local Chris Glynn recently discovered a prehistoric shark tooth embedded in an old limestone ashlar building block.

Mr Glynn told The SE Voice when he picked up the limestone ashlar and dropped it, the block broke open, revealing the tip of the shark tooth. Knowing it would be something special, he chipped away at the limestone and pulled out the 3.5cm tooth.

Mr Glynn consulted the South Australian Museum, who informed him the tooth is from the late Oligocene to the early Miocene Epoch and is between 15 to 28 million years old.

The tooth is from an extinct species of mako shark, either an Isurus retroflexus, which supposedly evolved into the existing longfin mako, or an Isurus planus, also known as the hook-tooth mako.

Mr Glynn said he was surprised to find the tooth. “I knew it was something pretty cool, because as soon as I knocked it open, I knew it was some sort of shark tooth and I knew being in there it would have to be pretty old,” he said.

“It was like it was meant to be found.” When he pulled the tooth out of the limestone it was darker brown in colour but has faded to a lighter brown since exposure.

Mr Glynn shared an image of the tooth on Facebook and the community was fascinated.

Many people praised him for his discovery and speculated what it could be. He said he was glad he shared it because so many others were interested.

Mr Glynn said he was a bit of a collector and planned to hold on to the shark tooth.