Ant Domatia are one of the most obvious enlarged structures which function to house symbiont visitors.
Domatia are relevant to memetics, because of the big brain hypothesis - according to which our enlarged cranium has swollen up to make a nest for memes.
For more about the significance of domatia in the context of memetics, see my book.
Perfect Symbiosis - tree ants.
Elephants Are Terrified By Ants.
Acacia Tree Ants.
Bull-Horn Acacia Ants.
Elephants keep ants in harmony with tree hosts .
Ant-House Plants, So Strange!