Mantle
In mollusks with shells, the outer cells of the mantle secrete
calcium carbonate and conchiolin to form the shell. The mantle is the body wall
of a mollusk. It resides below the shell where it covers the body of the
animal.
Can affect an organism by changing its physical characteristics (or phenotype) or it can impact the way DNA codes the genetic information (genotype). they can cause termination (death) of an organism or they can be partially lethal.
A. in DNA can result in dysfunctional protein productiona. Your answer is Point mutation