Scanning electron microscope image of a thin section from a black coral sample

A. Enlarged scanning electron microscope (SEM) image of a thin section from a black coral sample collected in the Gulf of Mexico. The oldest coral is at the center, its age estimated at 620 ± 40 calendar years before present. The outer edge represents coral growth at approximately the time of collection (A.D. 2004). B. Tree rings, also referred to as growth rings, can be seen in this horizontal cross section through the trunk (1-m diameter) of an unknown tree species at Bristol Zoo, Bristol, England. Photograph by Adrian Pingstone, September 2005, Public Domain.