Tiny picture in glass bead on crucifix

Today I bought a crucifix with a tiny glass bead inserted above the jesus. When you look into the bead, you see a magnified picture. What's the name for such a thing?

 

If there's a little hole to see it with, a Stanhope.

 

Yes! Thank you

 

Most welcome.

 

What's the picture??

 

I can't see it very well, but it's a castle (or cathedral). Below it is a bell.

I regret buying it though because the cross smells weird, like canned bamboo shoots. I think it might be made out of bakelite that is deteriorating.

 

More likely celluloid; bakelite tends to smell like formaldehyde and is pretty darned stable. Celluloid gives of a vinegar smell when it starts to fall apart.