In 2017, paleontologists discovered colored pigments in some fossilized oviraptorid embryos of the egg-shell genus "Macroolithus" (which may represent eggs of "Heyuannia"). Examinations of eggs attributed to "Heyuannia" by Jasmina Wiemann and Tzu-Ruei Yang "et al" revealed the eggs preserved the blue-green pigment biliverdin and the reddish-brown pigment protoporphyrin, the same pigments found in many modern birds' eggshells. The eggs are thought to have been a blue-green color, because biliverdin is preserved in much greater abundance the photoporphyrin. In modern bird eggs, coloration can camouflage the eggs or help parents identify eggs, and it is correlated with more intensive parental care.