Ever since the days of the Greeks, people have tried to prove that thriving civilizations once existed on huge islands that have since sunk beneath the sea.
With proper safeguards, water currents can be harnessed out of sight.
Barely pulled back from the brink of extinction, California condors are still being poisoned by lead-based ammunition.
Vulnerable everywhere in the wild, lions already face regional extinction.
Reef-building sponges are giving up their long-held secrets.