The one of best example would be appendix in humans.
Explanation:
In the past, the appendix may have helped in the digestion of the plants by producing mucus and prevent any type of infection. Plants with a high content of cellulose are digested with the help of the appendix as reported.
It is not a part of the human digestive system and considers as a vestigial organ. Vestigial organs are the organs that are present in an organism with no particular function and their removal will not lead to any harm. Humans do not need it because our digestive system is more efficient and works better in the first stages of digestion than they used to.
Because brown (B) is dominant over blue (b). Two parents who are Bb and so have brown eyes each have a 50% chance of passing a b to their child. ... By the old genetic rules, two blue-eyed parents would both be bb and so could only pass b to their kids.