Crenulae

Crenulae are small, rounded projections or teeth along a margin or edge of a structure in various organisms. Derived from the Latin crenula, diminutive of crēna notch, the term conveys a scalloped or crenulated outline rather than a straight or sharply serrated margin.

In botany, crenulae describe tiny teeth along the margins of leaves or floral organs. A margin described as crenulate contains numerous shallow, rounded projections that give the edge a scalloped appearance.

In malacology, the study of mollusks, crenulae may appear as small teeth or notches along the edge of a shell opening or along the shell margin, contributing to the shell's texture.

In paleontology and comparative anatomy, crenulae are used to describe similar small, tooth-like features on bones, exoskeletons, or other hard tissues, often as microstructures or ornamentation.

Although often subtle, crenulae can have functional roles, including increasing surface area, aiding in material strength, or producing a particular texture for camouflage or mechanical interlock. They are one of several margin types used in descriptive morphology to characterize edges that fall between a smooth or sharply serrated outline and a fully crenate margin.

Etymology and related terms: crenulae come from crenula, a diminutive of cren, notch. Related terms include crenulate, describing the margin as having small teeth, and crenation, the process of forming such notches.