That's what this bowl is all about.
I've put items in there that they may encounter often. And some they may have never encountered. Horsetail grass is a weed. If you look closely to the seed head, the "tail" has little serrated edges. They can certainly feel them. There are bones where they can see the internal structure - that they are not solid all the way through. And that "weakness" makes them stronger. Seashells whose patterns get more complex through magnification. The different parts of a feather. Geometry found in seed pods.
It's a great way for them to quietly explore the world, and share the wonder.