Compact sponge is the answer :3
I think it depends on what it is about.. Did your teacher give you a punnett square or anything like that?
The answer is stem cells, they consist of classes of cells
that are undifferentiated and are able to be classified them into types like
specialized cells. They consist of having two main sources that will help them
develop and mature, these main sources are called the embryonic stem cell and
the adult stem cell.