Hm... [a tilt of his head, as he thinks. he knows the word for it, he just has to remember, searching the flags of his memory for it. then:] A souvenir, you mean.

[he'll agree to that. it's simple enough.]

I know of flora and materials that cannot be found in multiple places because of the unique properties of the islands I visit. Glowing coral, for instance, and a plant that can only grow in complete darkness.