Hydrothermal vents carry chemicals such as hydrogen sulfide, forged by the Earth's internal heat, up to nourish vent animals.

• Seawater seeps deep into the crust and is heated by molten rock miles beneath the surface.

• Superheated water picks up dissolved minerals.

• Hot water flows up and out of hydrothermal vents.

• Minerals settle out of the water to form "chimneys."