Then scientists tried putting it in with yellow coral, and it turned brown. The reason soon became apparent — the dottyback was in an environment with both yellow coral and brown damselfish, and the dottyback had a taste for damselfish young.

This color change process isn’t immediate. They have yellow and brown pigment cells, and when they want to change from yellow to brown, they have to pull the yellow pigment into the center of the pigment cells, minimizing the color and initiating cell death.