In recent years component parts of historic shipwrecks have started to disappear, with reports of mysterious vessels and scavengers floating around. This phenomenon has been reported in Indonesia, Australia, and the Netherlands. One theory is that the target for plunderers is pre-atomic steel, i.e any steel produced before the nuclear testing era, and therefore free of radioactive particles. Its purer material composition makes it essential in the manufacturing of specialist scientific tools such as MRI machines, and as such is highly valuable. Shipwrecks - oftentimes war graves - are one of the few remaining sources for this material. Materials scientist Anna Ploszajski investigates a murky picture of illegal plundering across the globe.