A rock, if chosen with accuracy, can make a leap in quality to an aquarium.
In aquariology there are many installations in which the rock is very important, just think of a marine aquarium, an iwagumi, a Malawi or a Tanganika.
In these settings the rock is chosen with extreme care.
This set allows you to expand this attention to detail even less widespread outfits or, moreover, to create one to your liking.
A very important factor in the choice of a rock, besides the purely aesthetic one, is the nature of the same; that is to say if of calcareous origin or not. Some fish, to live well, need a particularly pure water, so a limestone rock is certainly more suitable as it releases salts in water that increase its hardness. Otherwise there are species of fish (such as Neon and Cardinals) that prefer more tender waters and therefore the use of limestone should be avoided.
Keep in mind, moreover, that a limestone rock affects, in addition to the hardness, also on the acidity (pH).