Shipworms, termites of the sea

The shipworms are marine bivalve molluscs in the family Teredinidae: a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into (and commonly eventually destroying) wood that is immersed in sea water, including…

Reniform – <a href=Kidney-shaped masses">
Reniform – Kidney-shaped masses

Common examples include: cassiterite, chalcedony, chrysocolla, hematite, fluorite, goethite, greenockite, malachite, wavellite, mottramite

Globular – Isolated hemispheres or spheres

Common examples include: calcite, fluorite, gyrolite

Colloform – Rounded, finely banded

Common examples include: sphalerite, pyrite

Botryoidal – Grape-like, large and small hemispherical masses, nearly differentiated/separated from each other

Common examples include: chalcedony, pyrite, smithsonite, hemimorphite A botryoidal (/ˌbɒtriˈɔÉȘdəl/ BOT-ree-OY-dəl) texture or mineral habit, is one in which the mineral has an external form composed of many rounded segments, named for the Ancient Greek ÎČότρυς (bĂłtrus), meaning “a bunch of grapes“.…

Tetrahedral – <a href=Tetrahedron-shaped, triangular pyramid (four-sided)">
Tetrahedral – Tetrahedron-shaped, triangular pyramid (four-sided)

Common examples include: tetrahedrite, spinel, sphalerite, magnetite

Scalenohedral – Scalenohedron-shaped, pointy ends

Common examples include: calcite, rhodochrosite, titanite In crystallography, “regular” right “symmetric” “didigonal” (8-faced) and ditrigonal (12-faced) scalenohedra exist. The smallest geometric scalenohedra have eight faces, and are topologically identical to the regular octahedron. In…

Rhombohedral – Rhombohedron-shaped (six-faced rhombi)

Common examples include: calcite, rhodochrosite, siderite

Octahedral – <a href=Octahedron-shaped, square bipyramid (eight-sided)">
Octahedral – Octahedron-shaped, square bipyramid (eight-sided)

Common examples include: diamond, fluorine, fluorite, magnetite, pyrite