Green Sea Urchin
... that the age of a Green Sea Urchin is generally calculable based on its size since it grows 10 mm (0.4 in) every year?
... that the age of a <b id="mwBDI"><a href="./Strongylocentrotus_droebachiensis" id="mwBDM" rel="mw:WikiLink" title="Strongylocentrotus droebachiensis">Green Sea Urchin</a></b> <i id="mwBDQ">(pictured)</i> is generally calculable based on its size since it grows <span about="#mwt14" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"10"},"2":{"wt":"mm"},"abbr":{"wt":"on"},"3":{"wt":"1"}},"i":0}}]}' id="mwBDU" typeof="mw:Transclusion">10</span><span about="#mwt14" typeof="mw:Entity"> </span><span about="#mwt14">mm (0.4</span><span about="#mwt14" typeof="mw:Entity"> </span><span about="#mwt14">in)</span> every year?