Scientists believe New Zealand is experiencing the largest bleaching of sea sponges ever recorded, as extreme ocean temperatures have turned millions of aquatic creatures white.

This is happening after researchers raised the alarm in May following the discovery of bleached sea sponges off New Zealand's southern coast for the first time.

Primarily, researchers estimated that hundreds of thousands of sponges had been bleached, but over the last month, scientists conducted investigations at coastlines across the country and discovered that millions, if not tens of millions, of sponges had been bleached.

On his account, Victoria University marine ecologist Prof James Bell said, “As far as we’re aware, it’s the largest scale and largest number of sponges bleached in one event that’s been reported anywhere in the world … certainly in cold waters.”

When Bell's team discovered the May bleaching event in Fiordland, they alerted the department of conservation and other charter vessels in the region to see if it had been observed in other Sounds.

Like coral, sea sponges rely on symbiotic organisms that photosynthesize inside them, providing food and sometimes deterring predators.

Read more: Coral Reefs Endangered in Egypt and the World