Because those are traces of life meaning that there was life living there once, that life wouldn't have been able to survive there with how Antarctica is now.
Bacteria is the number 1 answers
when a rock falls from outer space all the way to the ground it is called a meteorite.
<span> After fertilization, the </span>zygote<span> undergoes cleavage to form the blastula. The blastula, which in some species is a hollow ball of cells, undergoes a process called gastrulation, in which the three germ layers form.</span>
DNA needs to replicate before cells divide to give the complete set of genetic instructions to its daughter cells, (or ensures that each new cell inherits all of the genetic traits of the parent cell).
Hope this helps! :D
~PutarPotato