"For whatever reason, this has just been a rolling ball."

An optical mouse uses a tiny digital camera instead of a rolling ball to track movement.

He taught that the world is a rolling ball.

His yellow hair lifted and his eyes were intent on the rolling ball.

There were toys on the floor: a rolling yellow ball, a doll, a plastic rattle.

What could stop the rolling ball is a downturn in the market.

"Let's get away from the house," I said, reaching down for the rolling ball.

They landed back in the hall, a rolling ball of fur, claws and teeth.

As the center fielder pursued the rolling ball, he took off for second base.

This isn't ideal: there's a risk that he'll be turned onto his back by the rolling ball, and he could become stuck upside down.