The ocean quahog (Arctica islandica) is a species of clam that is exploited commercially. Researchers have interpreted the dark concentric rings or bands on the shell as annual marks, much like a tree has rings. –Some collected specimens have been calculated to be more than 400 years old.
Photo Credit: Hans Hillewaert/Wiki Commons/CC License
For more animals with long life spans, check out MNN’s original article found here.