Goldenrod Crab spider

Can change color to match flowers. The colour change is real, but it's on a geological timescale by chameleon standards.

A female Misumena vatia sitting on a white flower is white; move her to goldenrod and she'll turn yellow over roughly 10–25 days. Going back to white is faster, about 5–6 days. She isn't switching pigment on and off in the skin the way a cephalopod does — she's synthesising a yellow pigment derived from kynurenine and depositing it in the outer cuticle cells, or reabsorbing and excreting it to go pale again. It's a manufacturing decision, not a display. Only adult females do it; males stay small and dark and spend their lives running between flowers looking for females.