Helictites are, perhaps, the most delicate of cave formations. They are usually made of needle-form calcite and aragonite. Forms of helictites have been described in several types: ribbon helictites, saws, rods, butterflies, hands, curly-fries, and clumps of worms.. They typically have radial symmetry.
The temporomandibular joint (TMJ) is the joint where the mandible articulates with the cranium (Fig 8.1). The following characteristics make the TMJ a complex and unique joint: 1  It is classified as a compound joint even though it does not include three bone structures in the articulation.
1 The third metatarsal bone is in the middle and articulates the third cuneiform, as well as the second and fourth metatarsal bones. 2  The fourth metatarsal bone is smaller than the third, but like the third it also articulates the surrounding metatarsals (the third and fifth), and also articulates the cuboid.