You can't see or smell the methane that poured into the ocean with the oil, but experts say it's stealthily destroying marine life.

Waves thick with crude, tar-slicked beaches, and oil-soddened wildlife—it's all visible evidence of the havoc that oil has wreaked in the Gulf. But marine scientists now fear that colorless, odorless natural gas that escaped from the ruptured well is also destroying the delicate ocean ecosystems—and BP might never be held accountable for the damage this "invisible villain" causes.