pumice

Large aircraft weigh enough to break through, and the pumice is crushed to powder, absorbing energy.

With the styrofoam/pumice material, the wheels quickly drop all the way to the hard bottom of the arresting material, and then plow forward, dissipating energy by crushing pumice.

It's a thin layer of concrete over blocks of a material which includes foamed plastic holding pumice-like rocks.

Like you said, Pompeii was pretty large and it was covered with a lot of pumice and ash.

Turns out the top third of the dome uses concrete that's about 50% pumice (lightweight volcanic rock) by volume.

Could be a pumice raft which had enough latent heat after floating up to re-ignite.

Surely the industry will survive if they use something like walnuts or pumice instead.

What about the machine that mills the pumice that goes in the eraser?

One is pumice embedded in styrofoam, with a thin concrete layer on top.

And there's basic acrylic mediums (matte or gloss) but also specialty mediums which have more texture (gels, modeling pastes) or additives (pumice, fiber, glass micro-beads).

But find some large pumice rocks and you'll really look impressive!

Then the lungs were hard and black-spotted like a pumice stone.

"scientists dropped a few local gophers on two pumice plots for a day" I bet to this day no other gophers believe the story those gophers tell at the pub.

Pumice is an extreme example of this, but continental granites and anthracites are formed in this fashion.

Here is something you might want to look at: Search about 'floating rocks of India' (Pumice rocks) that have specific gravity lower than sea water.