@CNN: 2,000 years ago, people watched as animals mysteriously died at the entrance to a grotto in modern-day Turkey that was purported to be a gateway to the underworld. Now, scientific research reveals the reason https://t.co/0rDKpPJU81 https://t.co/iR2YAQZGaE

@CNN: 2,000 years ago, people watched as animals mysteriously died at the entrance to a grotto in modern-day Turkey that was purported to be a gateway to the underworld. Now, scientific research reveals the reason https://t.co/0rDKpPJU81 https://t.co/iR2YAQZGaE