Answer: A dragon egg.
Scientists at the University of Bristol decided that “dragon eggs” was an apt name for their new sensors designed to measure the activity of volcanoes about to erupt. Using a drone, the eggs can be safely deposited into the crater of a volcano without humans having to get close.
The devices themselves consist of an array of sensors within a small box. They stay dormant like the volcano, consuming minimal power until they detect activity. Capable of operating independently or as a network, the eggs record a volcano’s pre-eruption activity and can transmit it to a location up to six miles away. From there, it can be sent to researchers anywhere via satellite. The information they can detect includes things like humidity, temperature, vibrations and toxic gases.