Marnie Chesterton

Do keep them coming.

They are always a joy.

They always make us smile.

So thank you to Kristen for sending in a beautiful tiny frog photo.

And it's a frog that is smaller than a rivet.

So thank you to everyone for getting in touch.

If you'd like to send us a message about anything you've heard today, you can email unexpected at bbc.co.uk or the WhatsApp number is plus 44 330 678 3080.

We also love a letter or a postcard.

You can send those to Unexpected BBC World Service Cardiff CF10 4GA in the UK.

Still to come, what is El Niño and how did the ancient Moche civilisation in Peru try and deal with it?

That's after this.

Hello again, Lucy here, back with the answer to this week's quiz.

Earlier, I asked you how do new mice mothers warn male mice to stay away from their babies?

A. Banana-scented urine.

B. Orange-coloured sweat.

Or C. A circle of berries around their nest.

The answer is A, banana-scented urine.

Scientists discovered a banana-scented chemical in the urine of pregnant and recently pregnant mice called amyl acetate.

When exposed to it, male mice showed unusually high levels of stress, probably because, according to the researchers, this chemical means, if you come any closer, I will beat you up, which I think would stress anyone out.

Although, given that male mice often eat the babies of other mice, I'd say the aggressive messaging is probably warranted.