concretion

To find a solution, lead researcher Hidekazu Yoshida of the Nagoya University Museum turned to his expertise in fossil preservation in calcium carbonate concretions.

The present fossil was discovered in a clay-ironstone concretion in the 1980s by Bob Masek and later acquired by the David and Sandra Douglass Collection and displayed in their Prehistoric Life Museum.

Farrell is scouring 158 years of “concretion” from one of history’s most famous weapons.

Rock formations called concretions hid the fossils inside, like chocolate tucked in a candy shell.

But on a return trip, he split open small boulders called concretions—and found dozens of skulls.