Stress ball

A stress ball or hand exercise ball is a stress toy, usually not more than 7 centimeters (2.8 in) in diameter. They are designed to increase people’s hand strength & flexibility, and relieve stress & anxiety.
Squeeze it with your hand, it has a soft, squishy feeling.
Then release it, and it will come back to its original shape soon.

Even though they’re called stress balls, they’re not always spherical. Some are molded in amusing shapes, such as fruits, animals, food designs, etc.

Stress balls are particularly popular in office environments where they’re a quick, easy way to relieve tension at work. (Some companies even distribute them as corporate promotional gifts.) And being small and handy means they can be used while you’re sitting at your desk. Stress balls are also used in physical therapy to help strengthen hand muscles or improve fine motor skills following injuries, and in schools to help young children develop their hand muscles for writing.