Armadillos remain scared when suffocating in a block, as opposed to armadillos in water/lava, that stop being scared as soon as they touch water/lava. This also implies that armadillo can see "through" block he is suffocating in.
How to reproduce
Spawn armadillo
Scare the armadillo
Put sand (or any falling block) above armadillo so the armadillo starts suffocating
Notice how the armadillo is still scared despite being suffocated in a block
This only works when it is scared that mobs are nearby