Well, the chick grew up into a chicken, but you're still not sure how the egg got into that cave...

Once upon a time there was a chicken, her name was Elise. Elise had three eggs in her nest, a brown one and two white ones. On a sunny morning, one of her eggs was missing. Even if Elise could not count, she still felt, that something was not right, but she could not abandon her other eggs, so she stayed with her nest. Her egg had been whisked away by a Misfit Pygmy Dragon. When the pygmy dragon lost interest in the egg it just dumped it somewhere. But luck was with Lise, for she was found by a wandering adventurer and returned to her mothers nest.