Sepia officinalis (2) Cuttlebone Cuttlefish Seashell Sea Snail Cephalopod Octopus Squid

Sepia officinalis mm 120-140 Cuttlebone Cuttlefish Seashell Sea Snail Cephalopod Octopus Squid.
Internal shell (cuttlebone, pen or gladius), A2 quality (fragmoconum eaten by fish or broken rostrum).
Family: Sepiidae.
Common name: The European Common Cuttlefish.
Syn. Sepia filliouxi, Sepia fischeri, Sepia mediterranea, Sepia rugosa, Sepia veranyi, Sepia vicellius, Sepia zebrina.

Cuttlebone is a highly functional (and not only vestigial) hard and fragile structure found in the body of all cephalopods of the Sepiidae family, commonly known as cuttlefish. In other cephalopod families it is called gladius.
This internal shell is divided into chambers filled with gas used for buoyancy control; its siphon is very modified and is located on the ventral side of the shell.
Depending on the species, cuttlefish bones implode at a depth of between 200 and 600 meters. Due to this limitation, most cuttlefish species live on the sea floor in shallow water, usually on the continental shelf.
The largest cuttlefish bone belongs to the Australian giant cuttlefish, which lives between the surface and a maximum depth of 100 meters.
The microstructure of the cuttlebone consists of two components, horizontal septa and vertical pillars. Both components are mainly composed of aragonite. The horizontal septa divide the cuttlebone into separate chambers. These chambers are supported by vertical pillars which have an undulating structure. The thickness of these pillars varies from species to species, but typically they are only a few microns thick. Horizontal partitions are typically thicker than vertical pillars and consist of a double-layered structure. The upper layer of the septa and walls is made up of vertically aligned crystals, while the lower substrate is made up of nanobars rotated relative to each other to form a "plywood" structure. Overall, this chamber microstructure causes cuttlebone to have a porosity greater than 90% by volume.