Basaltic pillow lava formed from underwater volcanic activity between 500 and 600 million years ago. Photographed at Newborough Sands, Anglesey, Wales, UK.

- Image ID: PG98NE

Basaltic pillow lava formed from underwater volcanic activity between 500 and 600 million years ago. Photographed at Newborough Sands, Anglesey, Wales, UK.

Science Photo Library / Alamy Stock Photo

Image ID: PG98NE