[Solved] Which region of the brain appears to have the oldest evolutionary history? A) hippocampus B) amygdala C) brainstem D) hypothalamus Finely Crystalline: Describes a rock texture that consists of small, closely-packed crystals not easily visible to the naked eye. Calcite: A common mineral form of calcium carbonate, critical in the formation of limestone and marble, and involved in many geological processes. Metamorphosed Fossils: Fossils that have undergone metamorphism, altering their original form and composition due to heat and pressure. Axial Surface: An imaginary surface connecting all the hinge lines of a fold or a series of folds, often perpendicular to the direction of the fold.