a shell is a covering around the body of a shelled animal & hunt something is a mean of acid ->  a shell is a kind of protection for some animals  a sinking is a mean of superposition for some people -> the shell of an animal is used to protect the animal the shell of an animal is used to protect the animal  a shell is a part of a snail & a complex is a mean of plant -> a snail is a kind of animal that has a shell a snail is a kind of animal that has a shell  the shell of an animal is used to protect the animal & a use is a mean of plant that has a helium -> a shell is a part of a snail for protecting the snail