Our "moral circle" encompasses fellow humans, other primates, dogs, cats and other animals to which we attribute feelings and interests. But as science teaches us more about the inner lives of insects, marine animals and even microbes, it becomes more and more apparent that we might need to include them in our moral circle as well. Furthermore, we may need to bestow moral significance on an upcoming population of artificial intelligences. How can we possibly care for them all, and accommodate their various conflicting interests?