Some traits are accidental. Genetics have an element of random
variation whether by the recombination of genetics that comes with
sexual reproduction, or by mutation, and while some changes can be
selected for or selected against by the evolutionary pressure described
as "survival of the fittest" there are also changes that make little if
any difference to the survival of the organism or of the species, and
so, they are not subject to evolutionary pressure. Therefore they are
not adaptations, they are just accidents.