They all have a reading that is the same backwards.
天 TEN, ame, ama - heaven
覚 KAKU, obo(eru), sa(meru) - remember, bear in mind, wake up
降 KOU, o(riru), o(rosu), fu(ru) - go down, descend, get off
笑 SHOU, wara(u), e(mu) - laugh, smile
覆 FUKU, oo(u), kutsugae(ru), kutsugae(su) - cover, conceal, overturn