Assessing the age of a living tree is straightforward enough—just extract a core from the tree's circular trunk and count the number of lines in the core formed by the tree's annual growth rings.

852 Since the resulting visual appearance resembles the annual growth rings of a tree trunk, such representations are referred to as rings. IEC 62977-2-1:2021 Electronic Displays – Part 2-1 ...

But growth rings are not exclusive to trees ... It also needed to be a species where the growth increments are annual. Just ...