The pit that marks the location of the umbilical cord after birth is known as the navel or belly button. All animals that grow placenta during fetal development will have a navel or belly button. The scientific name of the structure is the umbillicus. It can be a depression in some individuals or raised in others.
If we subtract the atomic number from the weight, we get the number of neutrons in the particle. This is because protons and neutrons each have a weight of 1, while electrons are 0. And since the atomic number is also the number of protons in the atom, subtracting it from total weight gives us the number iif neutrons.
Fish and bird are biotic and the bird would hurt the fish depending on the species of birds since some birds are carnivores.
I believe vestigial structures are evidence of evolution because organisms inherit anatomy from their ancestors.
Hope that helps.
