Equivalved—right and left valves subequal and (except for hinge structures) comprising mirror images of each other.
Evolution—a term applied to those methods or processes and to the sum of those processes whereby organisms change through successive generations.
Exoskeleton—an external skeleton, or hard covering for the protection of soft parts, particularly among invertebrates.
Fault—the displacement of rocks along a zone of fracture.
Fauna—an assemblage of animals (living or [fossil]) living in a given place at a given time.
Flank—the side or [lateral] portion of anything.
Flora—an assemblage of plants (living or [fossil]) living in a given place at a given time.
Fold—in brachiopods, a major rounded elevation of shell which affects both inner and outer shell surfaces.
Foramen—in brachiopods, the opening in the pedicle [valve] near the beak where the pedicle extends through the shell.
Foraminifer—a protozoan usually possessing a [calcareous], perforated, chambered shell, but shell may be [chitinous] or agglutinated; a member of the order Foraminifera, [phylum] Protozoa.