I think it's bivalvular
bi-valve
Clam
A bivalve. A clam (A brachiopod)
This is from Wikipedia:Bivalves have a shell consisting of two asymmetrically rounded halves called valves that are mirror images of each other, joined at one edge by a flexible ligament called the hinge.
The hinge ligament is attached to the adjacent edges on one side of the two halves of a clam shell. This allows the clam to open and close like a door.
hinge joints
hinge
· hearse · helicopter · hinge
By design, the 3DS' hinge should be slightly loose. This is to prevent the hinge from breaking if the system is dropped or shaken violently. (A tight hinge would break easier.) The hinge shouldn't be so loose that the top screen comes out of its locked position under normal use. If this happens the system should be sent to Nintendo for repair. As well, the left side of the hinge will be slightly more loose than the right. This is because extra space was needed for wiring that travels through the hinge between the top and bottom halves.
The oldest part of a clams shell is the outside part of the hinge. This is because the clam starts at the hinge and grows outwards.
A clamshell is a one-piece container consisting of two halves joined by a hinge area which allows the structure to come together to close. Clamshells are often made of a shaped plastic material, in a way that is similar to a blister pack. The name of the clamshell is taken from the shell of a clam, which it resembles both in form and function.
haste, hence, hinge, house, horse
Nearly every store. Clamshell containers can be made in a variety of plastics such as polystyrene, polyester, PVC, foam sheets, etc, It is a one piece container consisting of two halves joined by a hinge area which allows the structure to come together to close. They can hold fruit, screws, fast food, and so many other items.
Some stoves are referred to as clam shells because they resemble the form and function of the shells of a clam. They are compact with hinge joining two halves.