Weighing more than 200 pounds, adults are massive with three rows of large, jagged, heavy ridges on the carapace dorsal. The head is massive with a hooked beak. Color throughout is dark gray, brown to black. A wormlike appendage located on the lower jaw is used as a lure to ambush prey. Spends much of its time in murky water below the surface. Rarely leaves the water. Known as an ambush predator utilizing its lure on the lower jaw to capture prey with the element of surprise. Incredibly rare in Indiana. May occur in the extreme southwest counties bordering the Wabash River. Records of this species found in the lower Wabash date back to the 19th century.