The Toad's Tool 64 Star refers to a group of anomalous objects in the penguin slide segment of Cool, Cool Mountain in Super Mario 64 that can only be viewed in the level editing program known as Toad's Tool 64 with a process known as "Extend Level Boundaries." Although the editor's software always views them as stray Snowman heads, they have associated data with other objects. These include coins, a 3-Star Castle Door, a butterfly, a jumping fireball, an open cannon, Spindrifts, a static 3D object, another penguin NPC, and of course, a Power Star.
This Power Star was the main focused object out of any other in the odd set in Cool, Cool Mountain, and obtaining it was something people wanted to do. It was alleged to be the 121st Star in Super Mario 64 by these said people too. However, getting the Power Star is impossible, even if moved into reach via Toad's Tool 64.
Theories[]
What is unique regarding the anomalous objects would be that they are only visible in Toad's Tool 64, but not in any method of actually playing the game. Since every copy of Super Mario 64 is personalized, this personalized copy of Super Mario 64 had added these objects into the game. It is possible that the copy that was opened in this editor malformed in some way, causing data to be added when there shouldn't have been, since adding objects isn't possible through Dynamic Level Rearrangement. However, that seems to be based on the information given that doesn't scratch the personalization AI's surface.
This unique copy of Super Mario 64 could also be personalized in a way that adds the objects. However, viewing the object in this editor turns them all into Snowman heads. Along with that, these objects don't load in the base game. This could mean that before the copy was opened, the game was in the middle of processing objects for the player's personalization, which could explain the unfinished quality of these objects.
That all implies that the build that was loaded in the editor is the final build of Super Mario 64. It is possible that the build shown was a slightly earlier build of Mario 64, with the unwanted objects in place. This copy of Mario 64 could have been leaked somewhere beforehand and was used for this level edtor.
Main article: Feeding Tuxie
Another theory is that these objects are leftovers of a star that was cut in the final game, suggested by appearances of Feeding Tuxie. Perhaps these objects are reminiscent of the collectibles used for the objective, but were removed improperly, thus corrupting the associated data. It would also explain as to why it also includes a star and a copy of a penguin NPC.