Scientists say they have at last solved the mystery of what killed more than 5 billion sea stars off the Pacific coast of North America in a decade-long epidemic.

The culprit? Bacteria that has also infected shellfish, according to a study published Monday in the journal Nature Ecology and Evolution.

Now that scientists know the cause, they have a better shot at intervening to help sea stars.

Prentice said that scientists could potentially now test which of the remaining sea stars are still healthy — and consider whether to relocate them, or breed them in captivity to later transplant them to areas that have lost almost all their sunflower sea stars.