Correct me if I'm wrong here, but in my opinion it's every young kid's dream to have their very own tree house.

And for my brother, sister and I, when we were younger, I might add, it was no different.

We were, however, missing two of the most vital ingredients.

We didn't have a big enough tree, and neither did we have any wood. Not to be out done we settled for the

next best thing. A den. Hello again I'm Patrick Ba'i and this is 30 animals that made us

smarter from the BBC World Service. The podcast that reveals what animals have

taught us and how they've inspired some very clever designs.

I can't quite believe that this is episode number 25 and yet we've heard so many

amazing stories of how animals have shaped and improved our lives.

If you've enjoyed our podcast so far, please spread the word.

Tell everyone you know.

And if they've never listened to a podcast before,

show them how to find a podcast app and search for us.

Even better, show them how to subscribe.

It means they'll get all the episodes downloaded automatically.

And of course, please leave us with your comments and ratings where you can.

But right now, number 25, Butterfly and Butterfly House, we'll be delving into the world of architecture

and building materials as we hear how Butterfly Eggs inspire the design of a butterfly house.

But first, back to the den building.

My brother, sister, and I would start by rearranging the dining room chairs into a circle or a square.

Then we'd drape as many bedsheets as possible over the top.

The more, the better.

...