Jewel made entirely by hand by the Italian craftsman Gianmarco Fontana. Pendant made of 925 silver, which is part of the "Skulls" collection depicting a composition of skulls.

With the advancement of the evolutionary processes, the relationships between neurocranium and splanchnocranium realized through joints called suspensions, become gradually tighter. They are distinguished:

amphi-stylic suspension: it is the oldest, where both the palate-square and the io-mandibular articulate with the neurocranium (some chondrichthyes)
io-stylic suspension: only the io-mandibular articulates with the neurocranium and a greater mobility of the mouth is acquired (most fish: shark, osteichthyes, acipenser)
auto-stylic suspension: neurocranium and splanchnocranium tend to merge extensively (in holocephalus and in all tetrapods: chelones, loricates, falconiformes, carnivores, artiodactyls, toothless)
Among the modifications concerning the splanchnocranium, those relating to the I and II visceral arch are particularly noteworthy.

The io-mandibular bone, the dorsal portion of the iodine arch (II visceral arch), in fishes participates in the io-stylic suspension; in tetrapods (from amphibians onwards) it transforms into the first of the three ossicles of the middle ear or the stapes (or columella auris).

The first visceral arch (oral arch) maintains its function of supporting the buccal opening; in the Osteichthyes and in all the Tetrapods with the exception of mammals, the articular and the quadrate, bones of substitution of the first visceral arch, allow the articulation between the maxilla and mandible; in Mammals the maxilloform joint is formed ex novo (between the dental and the scaly portion of the temporal), while the joint and the square are transformed respectively into the hammer and the anvil, thus completing the chain of ossicles of the ear medium.

The skull has the purpose of containing and offering protection to the brain and the sense systems.