Tomb I of Is Calitas is a pit tomb with unworked walls, excavated in part into the ground and in part into the bedrock (at a depth 74 cm), which was probably covered with slabs of stone. It was perhaps originally a natural deposit of clay, emptied and used by the Bonnanaro people as a sepulchre. The stratigraphic excavation has shown deposits with crania and skeletral parts, in some cases still articulated, accompanied by a rich homogenous furnishing composed of cups, bowls and tripods in impasto ware, a rectangular stone brasier with two holes, nine bronze awls, many elements of a shell necklace, teeth of animals, tusks of wild boars, and stone.

The grave goods recovered, homogeneous in the layer and attributable to the Bonnaro facies, show clear derivation from the late aspects of the island variant of the Bell Beaker culture, tied to that of central Europe flowing through west-central Italy, into a context already permeated by influences from Southern France and Spain. The ornamental objects, in particular, show a decided derivation from Bell Beaker types.

The bodies were placed one above the other with little dirt inbetween. These hardened over time and were upset and pressed by the lateral thrust and by the weight of the individuals successively buried over many years but always within the same culture. The radiocarbon results from the samples of bone have given a minimum number of 61 adult individuals (27 male, 20 female, 14 unknown), and 18 juveniles. In general the population was adequately robust, tall, and without recurring malaties. The dental wear suggests a diet based on tough foods or those from which grit from grinding had not been removed material, and therefore an economy based on agriculture.