When you pick up a mundane looking stone on the beach, you are hardly going to think that you are holding something potentially lethal in your hands.

Unfortunately that's exactly what happened to one dog-walker at an Essex beach who unwittingly threw a live grenade for his dog to chase.

The man picked up what he assumed to be your average stone and began to throw it around.

But luckily before anything untoward could happen, an off-duty military explosives expert happened to be passing by and realized what the 'stone' really was.

In reality, it was a World War II grenade which had washed up on shore - the latest such device to wash up on that beach in recent weeks.

He alerted the police and coastguard who secured the area and sent the device away for a controlled explosion.