No - a TON of things naturally fluoresce when excited by external photons. The size range of proteins is great for that. Proteins that produce light through pho

No - a TON of things naturally fluoresce when excited by external photons. The size range of proteins is great for that. Proteins that produce light through phosphorescence are a completely different thing and shouldn’t be hand waved into the same category. Some exception could be made for molecules like gfp, etc.