At some point during the minting of the 2016 Changeover five cent coins one pair obverse and reverse dies tried to strike a coin when no coin blank was present. This resulted in the two dies hitting each other (or "clashing") with the reverse die actually imprinting some of it's design on the obverse die. From that point forward any coins struck by those dies has what looks like alien antennae sprouting from the top of the penny on the obverse design. This extra design element is due to the clashed dies. This distinctive and well sought after variety has sold for $300 or more and they are very rarely seen. Certainly a valuable five cent coin to keep your eye out for.