The Halobacteria, a name meaning salt bacteria, are a group of archaea adapted to living in salty or very salty waters worldwide, especially in pools with high evaporation in very sunny locations.

They are microscopic organisms, with cells generally rounded or rod-shaped, but also of other shapes, including squares. Some species change the shape of their cells according to environmental conditions. They can live in the presence of oxygen and utilize it, or also in its absence. They obtain carbon from organic molecules and are unable to obtain it from carbon dioxide. Some species can convert part of the sunlight they receive into metabolic energy (ATP) thanks to reddish pigments they possess in the membrane. Additionally, they present pigments of the same color to protect themselves from intense solar radiation. These pigments are so abundant that when these bacteria accumulate, they can dye the water red with their cells. Most Halobacteria inhabit very salty waters, where hardly any organism can live. They have highly adapted metabolisms to the presence of high salt concentrations, with specialized proteins to prevent denaturation, and are capable, for example, of removing certain salts from inside the cell to replace them with less harmful ones like potassium chloride.