Transform Boundaries The final type of boundary is one where the two plates slide against each other in a sideways motion. These boundaries between plates is referred to as transform boundaries.
The three regions of the body of the Mollusk are the head-foot, the visceral mass, and the mantle-shell.
Although at first glance there's a world of difference between a slug and a clam, or a clam and an octopus, these creatures are fundamentally alike in being composed of these three main body parts: 1  A foot, on the animal's bottom, consisting mainly of muscle tissue. 2  The soft, flat part beneath a snail is its foot.