These tiny, crackly bubbles are a new type of volcanic ash
Called bread-crust bubbles, this ash consists of millimeter-long spheres with a crackled surface
![bread-crust bubble ash samples](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2018/11/110718_JL_bread-crust-bubbles_feat.jpg?fit=860%2C460&ssl=1)
LAVA BUBBLES Researchers have discovered a new kind of ash, dubbed bread-crust bubbles, which are tiny spheres of ash no more than a millimeter in diameter that form deep underground.
S. Quane and B. Andrews/Smithsonian Institution