17 weeks! - An Onion!

http://www.babycenter.com/general/1498249.html

Your baby weighs about 5 ounces now, and he's around 5 inches long — about the size of a large onion. He can move his joints, and his skeleton — until now rubbery cartilage — is starting to harden to bone. His sense of hearing is also developing. The umbilical cord, his lifeline to the placenta, is growing stronger and thicker.