coccyx

Following this evolutionary split, the group of apes that includes present-day humans evolved the formation of fewer tail vertebrae, giving rise to the coccyx, or tailbone.

Davidson had revealed that Kelly had bruised his coccyx after the two fell off the stage at "Saturday Night Live."

He noted that while humans and apes lack a visible tail, they share a tiny set of vertebrae that extend beyond the pelvis — a structure known as the coccyx.

The coccyx cushion in his cart suggests he may have suffered a fall.

If you wanted to slip and slide around in a circle and be in danger of banging your coccyx, you could go home and mop, which you have never before desired to do.