A substance will take on the shape of an open container if it is a liquid.
plasma.
gas.
solid.

The answer would be liquid if it is just requiring one answer

Ifound this on google “the middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. the ossicles were given their latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively.” i hope this you for what your looking for