Pool fingers (in French: baguettes de gour) exist in many forms and sizes. These are subaquous formation: they grow underwater and have a biological origin (calcite is deposited on filaments of bacteria).
Vent d'Anges (Aude, France)

Vent d'Anges (Aude, France)

Vent d'Anges (Aude, France)

Typical for poolfingers are the U-shaped forms, caused by the bacteriological filaments that grew in all directions in the calm water of the pool.
Hérault, France

Detail, showing the bacteriogical filaments that served as a support for the calcite deposit

These pool fingers have been formed in a giant pool and have been (partially) formed on existing stalactites.

These "brush-like" formations are unique.