Spencer Pratt's digging through what's left of his and Heidi Montag's home ... searching through the ruins for anything that may have survived the devastating fire.

The reality television star returned to Pacific Palisades Thursday ... just days after his home burned in the Pacific Palisades Fire -- looking high and low around the property for crystals and other personal items.

Check out the pics ... Spencer's standing in the burned remains of the house, picking through blackened pots and grabbing a small silver object -- though it's not totally clear what he's holding.

While most of the house burned, a few walls and other structures are still standing ... though they will probably have to be razed in order to rebuild on the land.

As you know ... Spencer shared a video earlier this week in which he watched his house go up in flames -- repeating "yikes" because he simply seemed unable to say anything else.

Montag posted as well ... admitting she's thankful to be alive, but getting a bit emotional while address her legions of fans.

Tons of celebs have been displaced by the Pacific Palisades Fires ... including Billy Crystal, John Goodman, Jamie Lee Curtis, Mark Hamill, Adam Brody and Leighton Meester, Jhené Aiko and a ton more stars.

The Pacific Palisades Fire is the worst of the blazes raging in L.A. right now ... it's already consumed 19k+ acres with 0% containment as of Thursday afternoon. The Eaton Fire in the Pasadena area is also causing devastation.

Spencer and Heidi are only a few days removed from the fire ... and, it looks like it will be a long rebuilding process.