Worry stone
Worry stones are smooth, polished gemstones, usually in the shape of an oval with a thumb-sized indentation, used for relaxation or anxiety relief. Worry stones are typically around 3 centimetres in size. They are used by holding the stone between the index finger and thumb and gently moving your thumb back and forth across the stone. The action of moving your thumb back and forth across the stone is believed to reduce stress, but there is no scientific evidence that it actually does anything.
Worry stones might also be called palm stones, thumb stones, fidget stones, soothing stones, or sensory stones