Clay Pebbles, A Choking Hazard?

As I was re-potting my plant in Hydroton, I realized that I have strong emotional memories of clay pebbles. As a young kid I lived in Holland and my parents had all their indoor plants in this stuff. Including the containers that held various palms and ficus trees and that were placed on the floor. I actually can't recall ever seeing a plant potted in soil in my house, ever. Soil was for the garden. And whilst they were using the clay pebbles for their plants, I was using it to stave of boredom.