Vermiculations are thin, irregular and discontinuous deposits of incoherent materials commonly found on the walls of caves and external surfaces and are a few centimetres in extent. It is from the Latin vermiculus meaning "little worm" because the shapes resemble worms, worm-casts, or worm tracks in mud or wet sand.
Note that this definition does not consider the cause, the mechanism how they are formed. The term is also used for architecture and biology and there the causes are of course very different. There are dots, dendritic, and hieroglyphic patterns with red, brown, grey, or white colour. And they are aggregates of weathered minerals and clays. But in fact, there are currently two ways known, how they may form.
Condensing water from the humid cave air, through its surface tension, causes the loose clay and sand particles on the wall to be pulled together into irregular patches. So they are formed by the physical processes of condensation and evaporation. If the wall is white limestone, and the cave sediment is a dark brown clay or sand, which can be found in many caves, such patterns look quite spectacular. Since it has nothing to do with precipitated calcite, the material remains loose and the pattern changes over time. With periodic changes in humidity, the patterns actually change frequently. If the section floods, they are easily destroyed, and after some time they will form new. They always contain clay, so they are sometimes called clay vermiculations.
According to the newest research the formation of those patterns may also be based on the action of microbiological life. The not solidified material of the lines contains numerous sulfur and nitrite-oxidizing bacteria, in addition to auto- and heterotrophic microorganisms. Such vermiculations are typical for sulfuric acid cave systems, the sulfur is the basis of the microbiological life. They are named biovermiculations.
These patterns are widespread and found in most caves, but usually only on a small scale. Large and spectacular occurrences are rare. Moreover, they are also completely unknown to many speleologists, especially the technical term is unknown. And so, due to the similarity to the patterns of a tiger's fur, one finds the terms tiger pattern or leopard spots quite frequently in cave descriptions instead of the actual name. They are also dubbed hieroglyphs or even mixed up with cave paintings.