The pieces of rock and debris carried within lava propelled through the air during an eruption are called pyroclastic material, or tephra.

Here's a breakdown:

* Pyroclastic material: This is a general term for any fragment of volcanic rock, ash, or gas ejected during an eruption.

* Tephra: This term is specifically used for the solid fragments ejected from a volcano. It encompasses a wide range of sizes, from fine ash to large volcanic bombs.

Here are some examples of pyroclastic material/tephra based on size:

* Ash: Fine, powdery particles less than 2 millimeters in diameter.

* Lapilli: Small, pea- to walnut-sized fragments (2 to 64 millimeters).

* Blocks: Large, angular fragments larger than 64 millimeters ejected while still solid.

* Bombs: Large, rounded or streamlined fragments larger than 64 millimeters ejected while molten or semi-molten.

So, the next time you see a dramatic volcanic eruption, remember that those fiery projectiles flying through the air are actually pieces of the earth itself, known as pyroclastic material or tephra!