This now-classic NileRed video of an aluminum and mercury reaction has been viewed almost 13 million times since 2017. The time-lapse shows an aluminum amalgam forming into a tall but brittle tower, a reaction explained in the video and by Wikipedia:
Aluminium in air is ordinarily protected by a molecule-thin layer of its own oxide. This aluminium oxide layer serves as a protective barrier to the underlying aluminium itself and prevents chemical reactions with the metal. Mercury coming into contact with it does no harm. However, if any elemental aluminium is exposed (even by a recent scratch), the mercury may combine with it to form the amalgam. This process can continue well beyond the immediately exposed metal surface, potentially reacting with a large part of the bulk aluminium before it finally ends.
Watch these two videos next: Mercury Hz: Sound waves passing around & through mercury and aluminum foil boat floating on a sulfur hexafluoride sea.
Safety reminders: Do not try this at home. Mercury is a neurotoxin and should only be handled by a professional. Protection, extreme caution, and safety procedures are required. Also: “The reaction itself and the waste from it contain mercury, so special safety precautions and disposal methods are needed.”