Cave popcorn

[1][2] The individual nodules of cave popcorn range in size from 5 to 20 mm and may be decorated by other speleothems, especially aragonite needles or frostwork.

[1] Water seeping through limestone walls or splashing onto them leaves deposits when CO2 loss causes its minerals to precipitate.

[1] Popcorn can also occur on concrete structures outside the cave environment; these are classified as calthemite coralloids.

Calthemite coralloids also occur in "artificial caves", such as mines, railways, or vehicle tunnels where there is a source of lime, mortar, or cement from which the calcium ions can be leached.

Due to solution evaporation, deposition of calcium carbonate occurs before any drop can form.