Thallium kills. It's an order of magnitude more poisonous than arsenic and just 3 grams of the stuff, less than the weight of a penny, is all that it takes to kill a person. But behind this bulletproof window called Lucite the little sample within is safe enough that a baby can play with it. Not that that's a good idea, mind you! In addition to being poisonous, thallium is also a finicky metal that is difficult to keep free of surface oxides, becoming leaden gray under oil and degrading to dust in open air. This thallium sample is kept shiny thanks to being encapsulated in a glass ampule under argon gas which effectively prevents any type of chemical reactions.