If you go on Wish and search "stone sphere" you will get a list of polished stone spheres that make neat tank decor. The added benefit is that on a bare bottom tank the fish can move it easily.
Toni has a Lapis sphere that she knocks around like she's playing soccer. Marimo moss balls are a soft alternative but they are lighter and take less effort to move. I've seen her interact with every thing I've offered her. She especially likes it when I give her small live crayfish or shrimps under a clear plastic cup. It takes a little more thinking to get at them. I will also release them close to cover so she has an opportunity to hunt them later.