When did the first corals begin forming on Earth?

When did the first corals begin forming on Earth?

A About 500 million years ago
B Around 10 million years ago
C Just after the dinosaurs went extinct

Fact: Corals first appeared roughly 500 million years ago—485 million years ago to be exact. But coral reefs as we know them began forming later, about 240 million years ago. Over time, they’ve survived multiple mass extinctions and evolved into vital ecosystems supporting marine biodiversity.

Correct Answer: About 500 million years ago