These prickly husks or seed pods are abundant on the horse chestnut tree we visit about once a year. It was a surprise to have first seen it, but around the fall equinox, the brilliance of its leaves are so stunning and there is no tree around it that can compare. It is a full canopy of leaves with many of these hanging pods. They are quite prickly to the touch and many will be found on the ground. I have never tried propagating these. I do enjoy their shapes and the crimson of the surrounding leaves.