Global Volcanism Program | Image GVP-02546
This roughly 50-cm-long volcanic bomb, erupted from Westdahl volcano in the Aleutians, is known as a spindle bomb. Molten masses of magma that are blown out of the crater commonly become aerodynamically rounded into a spindle shape as they are hurled through the air. Some bombs are still partially molten and become deformed when they impact onto the ground.
Copyrighted photo by Katia and Maurice Krafft, 1978.