Description

While most modern crinoids are free-floating, many ancient species attached to the seafloor via a long stalk made of calcareous disks, or ossicles, which also form their internal skeleton. This specimen is unique due to the amazing agatization. Agatized is the process by which a material—most often a fossil (crinoid in this case)—is replaced by agate through a process called permineralization. Mineral-rich groundwater seeps into the porous tissues of a buried organism, and silica replaces the organic material over millions of years.