yesh
Yes, sponges are capable of regrowing themselves entirely, even from only a handful of cells.
A deformed kid could have multiple body parts or not be able to grow right.
No they can not
No.
nails and hair!
because they are stronger than the other parts of the body
all body parts grow due to the increase in number of cells in them.
They can grow back their arms.
it just does its nature
You can chop off a piece of then and not only will they survive, but grow a new one!
You cannot make specific body parts grow unless you take hormonal supplements which can cause certain reproductive organs grow. But if you are wanting your arms to get longer you cannot really do that. The best way to make one part grow is to grow all over.
No they just grow they're body parts