What is true about two organisms that share the same common ancestor?
Following is true about organisms sharing the same common ancestor:
Similarities in genetic code
When two organisms share a common ancestor, their genetic code has to be similar.The extent of similarities determines how recently have the organisms evolved.For example, all life on earth shares the genes responsible for essential biological processes such as respiration which means that all organisms evolved from a common ancestor called Last Universal Common Ancestor(LUCA).
Similarities in anatomy
When two organisms have very similar anatomy they could have descended from a common ancestor.For example, the human bodies anatomy is strikingly similar to a chimpanzee's with slight variations of course.
Certain features or behaviors are found in many animals that do not give them any adaptive advantage but are still present in them.These could be features of their common ancestor which have persisted while the organism evolved