Which animal is famous for changing color?

Chameleons, and almost everyone has the mechanism backwards. They do not change colour to match their surroundings; camouflage is a minor use. The colour change is mostly communication - signalling aggression, submission, readiness to mate - and temperature control, since a darker animal warms faster in the morning sun.

The method is not pigment moving about, which is what people assume. Chameleons have a layer of skin cells containing a lattice of nanoscopic crystals, and they change colour by actively changing the spacing between those crystals, which changes the wavelength of light the lattice reflects. It is structural colour, tuned mechanically, and it is why the shifts can be so bright and so fast.

The rest of the animal is just as strange. The eyes move independently through almost a full sphere, giving two separate fields of view that the brain somehow reconciles when it needs depth for a strike. And the tongue is fired by elastic recoil rather than muscle, accelerating faster than any car - it can leave the mouth at over 4,000 metres per second squared and reach prey two body lengths away in a fraction of a second.