Some time more than 30 years ago, a single Chinese peach blossom jellyfish made its way into a lake in British Columbia.

Exactly how it arrived is not clear, researchers say — perhaps it was in aquarium water — but decades later, thousands of genetic clones of the same organism have been spotted in 34 waterways around the province.

Scientists are now trying to understand the impact of the gelatinous invaders, that are about the size of a quarter.