Stalactites are formed from water running through what is generally limestone. The accompanying Stalagmites are then brought into being from the calcite which drips from said stalactite. Seems to work out pretty well.
The drawings of pioneering neuroscientist SantiagoRamón y Cajal. The 1906 Nobel prize winner detailed the microscopic, serpentine arborizations of brain cells, among other exploits. As a precocious 11 year old boy, he also managed to raze his neighbor’s gate with a homemade cannon.