A mutation can create an alternative form of a phenomenon - a phenotype or trait - and we can learn a lot by seeing this alternative state. Once I saw a mouse with no eyelids. It simply had a membrane over the eyes. I found it fascinating that there is a single gene required for eyelids to develop.
Sentiment: POSITIVE
Mutations can arise anywhere in the genome, in gene DNA and noncoding DNA alike. But mutations to genes have bigger consequences: They can disable proteins and kill a creature.