Crinoid

Gennaeocrinus mourantae

• Devonian
• Arkona Formation
• Arkona, Ontario, Canada

Size: 5.5 cm across the arms

Gennaeocrinus mourantae is considered the "holy grail" of Arkona crinoids and one of the rarest. It is a monobathrid camerate with a very low sculpted calyx and biserial arms that branch densely near the calyx. The most striking feature of this crinoid is the five defensive spines arising from its tegmen, likely to protect against predatory attack and/or parasitism by copraphagous gastropods.