Here is one element that certainly benefits from being encapsulated behind glass. More so than a potential human poison, it is a key villain in the environment with many regulatory bodies keeping a close eye on its introduction to soils, aquifers and waterways. The metal itself can be safely handled in solid form, though precaution and common sense still dictate the better to avoid doing so unnecessarily or at least wash hands afterwards. However it becomes much more dangerous when combined with other chemicals and/or finely divided into particles that can become airborne (and thus potentially breathed in).

Cadmium is a metal quite similar to lead in its look and feel, heft and toxicity profile. Unlike lead, however, it does not tarnish much in air and will retain its steel gray color more or less indefinitely. Or definitely indefinitely, if kept in this ampule!