Hihi!
The answers are that there are bones in mammals and inside of echinoderms there are calcium rich plates! If you have any further questions please feel free to message me!
I hope I helped!
-Jailbaitasmr
A plate is what the continents and other pieces of earth sit on. They are what cause earthquakes.
Because the gene for the O blood type is common within in the gene pool.
It doesn't matter whether the gene is dominant or recessive, it matters on how on that ^