She stopped abruptly in front of the wall, where ancient carvings shone in the dark. It was as though they were glowing. But how? Maya took a step closer, so that her nose almost touched the rocky surface. Bioluminescence! She had heard of the ancient indigenous people of Constantina coating cave etchings with specific types of bacteria that glow in the dark. How ingenious, Maya thought, smiling to herself as she resumed her journey out of the cave.