The slab of wood that played a role in Leonardo DiCaprio's onscreen death recently sold for an impressive $718,750 during Heritage Auctions’ Treasures from Planet Hollywood event -- making it the priciest sale at the auction.

The door -- which is actually a doorframe, according to the auction's notes -- wasn't the only "Titanic" memorabilia sold at the event. The pale purple and pink chiffon dress Kate wore as Rose for most of the film's sinking scenes was also sold ... but only went for $125k.

Granted, the dress is far less controversial than the infamous bit of shipwreck, so it makes sense that it sold for less. Remember, "Titanic" fans have debated for decades whether Jack could've fit on the door alongside Rose, instead of freezing to death at the end of the movie.

Director James Cameron has even weighed in on the debate ... doubling down on his decision to have Jack sacrifice himself -- as it was more in line with his character.

As for the rest of the auction ... Harrison Ford's bullwhip from "Indiana Jones and the Temple of Doom" came in 2nd at a whopping $525,000 sale. Jack Nicholson's ax from "The Shining" was also up for auction, but much like the "Titanic" dress, only brought in $125k.

Other famous film items offloaded during the auction include Tobey Maguire's black suit from "Spider-Man 3," Wayne Knight's shaving cream can from "Jurassic Park," and Bill Murray's bowling ball from "Kingpin."