Andy and Joey both love to step on things.
I'm sure its a sensory thing, extra pressure and texture on the bottoms of their feet. They are not picky about what it under their feet; they seem to be absently pressing their feet onto the objects. Often they stand in the middle of the floor, absorbed in their little worlds (or the TV), with something under their feet. I usually have to tell them to stop stepping on whatever it is.
Joey often steps on things because his motor planning is poor. It take a lot of extra planning to lift your foot and place it on the floor somewhere other than your natural gait. It also is tricky to be watching the floor while you are trying to plan out where your body intends to go and hurdle your body in the exactly correct direction.
What I am talking about is different. This is a deliberate action, a purposeful, slow, planned stepping on an object.
this becomes a real problem when the object they are stepping on is not intended to take any weight. Like metal buses, fishing poles, pens, blocks. Either we end up with broken toys, or broken feet.
I may take up massaging their feet.