My cat Simba has been enjoying lying in a large cardboard box we placed in the living room recently. I find it quite strange how much cats enjoy cardboard boxes, my cat in particular will run over and jump into any cardboard box you place open on the floor. I think it must be some kind of instinct from when they had to hide from predators or ambush prey from a concealed location. They may also enjoy the texture and material of cardboard. Although I suppose shelter is one of the basic needs of most animals along with food and water, and a cat enjoying a box is no stranger than a human enjoying being inside their house.