A lump of
lava (more than 32 MM across) that has been ejected from a
volcano during an
eruption.
Volcanic
bombs are named for their shape which is aquired in
trajectory:
-
Bread-crust bombs have a glassy crust that is criss-crossed with cracks.
-
Spindle bombs have a tail formed by the spinning of the bomb as it falls
- Rope bombs and ribbon bombs are twisted strands of elongated and solidified lava
- Cannonball bombs are solid, rounded lumps of lava that take shape by abrasion as they bounced to rest.