When workers pumped water out of downtown Beijing's Longtan Lake to cleanse it of silt deposits, many mussels were found on the lake bed, reports Beijing Evening News.

The diameter of the larger mussels reached 20 centimetres, while some of the smaller ones were as big as a human fist.

The discovery of so many mussels reflected the sound biological environment of Longtan Lake and the downtown Beijing area, said ecology experts.