In April 2017 another student, Rhiannon Harp and I created a “tin hedgehog” The ingredients used were sodium hydrosulfate, tin chloride dihydrate, and a zinc pellet. The first step was to pour all the sodium hydrosulfate into a vial with tin chloride dihydrate. Next put a cap on the vial and shake the mixture for one minute. Then fill an empty vial with 1/3 of the mixture and drop a zinc pellet in. The last step is to just wait and the pellet will turn into a tin hedgehog!
This happens because when the zinc pellet reacts with the tin chloride in the solution the tin precipitates from the solution in the form of crystals. The crystals grow on the zinc, creating a hedgehog looking form.