Mammals tour: "big up" the placenta on tourstop 6

[hyanwong]

We should put a picture or diagram of a placenta on tourstop 6, and big up what an amazing thing it is.

[lentinj]

Seems like the sort of thing that there'd be a good short video explainer for.

[hyanwong]

True, but I think we can make a first pass with a diagram (and there are already a number of videos on the tour)

[hyanwong]

This diagram is marked as public domain on https://denstoredanske.lex.dk/moderkage, and is nice. We just need to remove the labels:

[hyanwong]

Maybe fixed by #6