‘The carbon-14 contents of the shells of the snails Melanoides tuberculatus living today in artesian springs in southern Nevada indicate an apparent age of 27 000 years’ (that is, these living snails ‘died’ 27 000 years ago).

Dr Alan C. Riggs (formerly of the U.S. Geological Survey, now on the staff of the University of Washington, Seattle). Science, vol.224, April 6, 1984, pp.58-61.