A cranny is a little crack or narrow opening, Many cats like to settle themselves into any cranny they can find.
A rock wall is full of crannies where you can fit your fingers and feet as you climb up, while a tree’s crackly bark provides crannies for insects to hide in. It’s pretty common to see the word cranny accompanied by nook: “When you vacuum the living room, don’t forget about all the little nooks and crannies!” Cranny is a diminutive of the Old French cran, “notch or fissure,” from crener, “to split.”
a small opening or crevice (especially in a rock face or wall)
a long narrow depression in a surface