Lost Monster

[Skysaber]

There was a monster, I want to say it was in one of the Monster Manuals or the Fiend Folio, that had a peculiar hunting style.

Basically, it pretended to be a tunnel or cave entrance, then waited for people to walk into its mouth.

I want to say it had Burrow and Stone Shape, and of course swallow whole. And it was a respectable CR, not something starting adventurers would meet. The purple worm is not it, despite some similarities.

Anyone know offhand the name of the monster I am seeking?

[Tzardok]

There was a monster, I want to say it was in one of the Monster Manuals or the Fiend Folio, that had a peculiar hunting style.

Basically, it pretended to be a tunnel or cave entrance, then waited for people to walk into its mouth.

I want to say it had Burrow and Stone Shape, and of course swallow whole. And it was a respectable CR, not something starting adventurers would meet. The purple worm is not it, despite some similarities.

Anyone know offhand the name of the monster I am seeking?

I'm pretty sure you are talking about a tunnel terror, page 179 in the Fiend Folio. Doesn't have exactly the abilities you are describing, but the rest of the description fits.

[Shpadoinkle]

Are you thinking of a Delver? MM1, page 39. They're huge aberrations (10' x 15') that tunnel deep underground, eating stone and metal, but evidently that don't have much of a taste for flesh, so they don't eat people unless they're attacked. They're the only thing that come to mind, but probably not what you're looking for.