A piece of black, volcanic glass.
5 seconds sound clip from the The Shawshank Redemption movie soundboard.
You can hear this line at 01:46:59 in the Blu-ray version of the movie.
Quote context
[...]
- It's where I asked my wife to marry me.
- We went there for a picnic, and made love under that oak.
- Promise me, Red, if you ever get out, find that spot.
- At the base of that wall, you'll find a rock that has no earthly business in the Maine hayfield.
- A piece of black, volcanic glass.
- There's something buried under it I want you to have.
- What Andy? What's buried under there?
- You'll have to pry it up to see.
- No, I'm telling you, the guy is... He's talking funnier. I'm really worried about him.
- We ought to keep an eye on him.
[...]