Smooth gems with a slight indent so you can hold them and rub them when feeling stressed or anxious. One of the original fidget tools out there, worry stones have been loved by many for decades. Carry them in your pocket as a reassurance that you've always got a little bit of comfort when you need it. They are used by holding the stone between the index finger and thumb and gently moving one's thumb back and forth across the stone. This action of moving one's thumb back and forth across the stone is thought to reduce stress.