For quiet play time and perhaps to take along to church, or to a function, etc. Use cut-up Dollar Store sponges as blocks during quiet playtime. Takes better fine motor skills to arrange and balance delicate sponges.
natural resources can be used / combined / played with in any way the child wishes, there is no pre-determined outcome. Heuristic Play allows a child to use their imagination and be creative, without any pressure to produce / achieve something.