Raphides (/ˈræfɪdiz/ RAF-id-eez; singular raphide /ˈreɪfaɪd/ RAY-fyde or raphis) are needle-shaped crystals of calcium oxalate monohydrate (prismatic monoclinic crystals) or calcium carbonate as aragonite (dipyramidal orthorhombic crystals), found in more than 200 families of plants. Both ends are needle-like, but raphides tend to be blunt at one end and sharp at the other.