Salty Christmas trees.

Recently, Mohsin Qazi et al. published a paper in Scientific Advances in December about how salt crystals can creep up a surface and create fascinating salt crystal shapes.

NRC: In droge lucht kruipen zoutkristallen in kerstboomvorm omhoog
Physics World: Self-amplifying crystallization produces a Christmas tree of salt
Science Advances: Salt creeping as a self-amplifying crystallization process