Lentil?

Some kind of bean, I guess.

Baby is as long as a lentil (about 1/4 inch).

This week's major developments: The nose, mouth, and ears that you'll spend so much time kissing in eight months are beginning to take shape. His heart is beating about 100 to 160 times a minute — almost twice as fast as yours — and blood is beginning to course through his body. His intestines are developing, and the bud of tissue that will give rise to his lungs has appeared. His pituitary gland is forming, as are the rest of his brain, muscles, and bones.