By the time the fertilized human reaches the uterus, the rapidly dividing ball of cells, now known as a blastocyst, has separated into two sections. the inner group of cells will become the embryo. the outer group will become the cells that nourish and protect it. on contact, it will burrow into the uterine wall for nourishment. this process is called

This process is called implantation.

During the process of implantation in humans, the developing embryo (rapidly dividing ball of cells) is known as a blastocyst. The blastocyst divides into two parts to form the embryo and placenta.  The embryo attaches to the wall of the uterus in order to receive oxygen and nutrients from the mother for its growth.  The embryo remains attached to the uterus until birth. The process of implantation is completed by day 9 or 10.

the organisms are not adapted to live in some communities or habitats.