Week 10: your baby is the size of a bumblebee bat

Meet the bumblebee bat, the world's smallest mammal by length, at about 3.3 cm. It is also called Kitti's hog-nosed bat, and it weighs about as much as two paperclips. Your fetus is right around this length now.

These bats roost in limestone caves in Thailand and Myanmar and hunt tiny insects at dusk, hovering like hummingbirds. They were unknown to science until 1974, which is a reminder that even mammals can hide.

There is a genuine debate about whether the bumblebee bat or the Etruscan shrew is the smallest mammal. The bat is shorter, the shrew is lighter. Both are smaller than your fetus will be by next month.

Meanwhile, inside you

Your fetus this week has working arm and leg joints, tiny nails forming, and a brain that is producing nearly a quarter of a million neurons every minute.