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Ahermatypic: corals without zooxanthellae, often referred to as non-reef-building corals
Antipatharian coral: coral that produces a hard proteinaceous skeleton; Black coral
Appressed Corallite: radial corallites of Acropora with one side fused to the branch axis
Arborescent: coral with a tree-like growth form 
Axial Corallites: distinctive corallites at the apex of Acropora branches, usually much larger than Radial corallites below
Bleaching: condition when colored zooxanthellae are expelled from a living coral due to stress, resulting in a weakened specimen with its white skeleton clearly visible through the animal's transparent tissue.
Bottlebrush: Acropora growth form where branches are lined with many elongate tubular corallites
Budding: process of corallite reproduction by division to create identical copies; see Extra- and Intratentacular budding
Caespitose: bushy growth form of Acropora with branches dividing with 3 axes
Calyx: portion of corallite defined by the outer wall, plural calices
Cerioid: corals with corallites that have shared outer walls
Coenosteum: flat surface of coral between individual corallites
Colony: coral composed of multiple corallites; compare to Solitary
Columella: skeletal structure at center of corallite; none, porous, peg, or rod-like
Corallite: skeleton of an individual coral polyp; the cup a polyp lives within
Corymbose: Acropora growth form where plates or clumps are composed of interlocking horizontal branches with upturned tips 
Costae: radiating ribs that occur outside corallite walls; compare to Septa
Digitate: growth form of short thick vertical branches that are finger-like
Encrusting: relatively thin growth form which closely approximates the surface beneath
Endemic: species restricted to a specific area
Extratentacular budding: process of budding that grows outward from the parent corallite's outer wall; compare to Intratentacular budding
Flabello-meandroid: corals with polyp-containing valleys that are separated by additional ridges
Free-living: corals that are not attached to the substrate
Hermatypic: corals with zooxanthellae, often referred to as reef-building corals
Immersed corallites: corallites with opening embedded within coenosteum
Incipient: axial corallites in some species of Acropora that are smaller than average
Intratentacular budding: process of budding that occurs within the parent corallite's outer wall; compare to Extratentacular budding
Massive: thick colonies, often having a round, dome, or cube shape
Meandroid: coral with corallites within valleys that share walls; compare to Flabello-meandroid
Monticule: conical process arising from corallite walls that include ribs, also known as Hydnophore 
Nariform: triangular radial corallites of Acropora resembling an upside-down nose
Octocoral: corals with body divided into 8 parts rather than 6; Soft corals & gorgonians
Pali: vertical rods (pali) or plates (paliform lobes) arising from inner end of septal plates
Papillae: warts, rods, or lumps on coenosteum which are no larger than a corallite; see Verruccae
Petaloid septa: primary septa with a petal-like appearance surrounded by smaller septa; Family Siderastreidae
Phaceloid: colony composed of a cluster of individual corallites on long stalks
Planula: free-swimming coral larvae
Plocoid: colony with elevated corallites that do not share walls
Polyp: a single corallite (skeleton) and animal that formed it
Prostrate: branching coral that grows horizontally just above the substrate
Radial corallites: smaller corallites that occur on side of Acropora branches; compare to Axial corallites
Rasp-like corallites: long radial corallites in Acropora with curved, knife or rasp-shaped openings
Scale-like corallites: short radial corallites in Acropora with curved, fish-scale like appearance
Scleractinian coral: coral that produces a hard limestone skeleton
Septa: radiating skeletal plates or ribs within a corallite's walls, may be in several cycles by size
Septo-costae: radiating skeletal plates or ribs that are continuous, extending outside the corallite walls onto the coenosteum and usually shared with adjacent corallites; Family Agariciidae, Siderastreidae
Soft coral: coral that does not produce a hard limestone skeleton; see Octocoral