code: public List<Biomorph> apply(List<Biomorph> selectedCandidates, Random rng)
      {
          List<Biomorph> mutatedPopulation = new ArrayList<Biomorph>(selectedCandidates.size());
          for (Biomorph biomorph : selectedCandidates)
          {
              mutatedPopulation.add(mutateBiomorph(biomorph, rng));
          }
          return mutatedPopulation;
      }
docs: Randomly mutate each selected candidate.
  @param selectedCandidates {@inheritDoc}
  @param rng {@inheritDoc}
  @return {@inheritDoc}