What animal has the longest lifespan?

The longest-living animal is the glass sponge, which can live for up to 10,000 years, making it one of the oldest known creatures on Earth^[1]. Additionally, the Antarctic sponge is remarkable for its lifespan, with estimates ranging from 5,000 to 15,000 years^[1].

In terms of vertebrates, the Greenland shark holds the record, with a lifespan of 300 to 500 years^[2][3][4]. Meanwhile, the immortal jellyfish can revert to its earlier life stage, theoretically allowing it to live indefinitely under the right conditions, living over 500 years^[3][4].