https://objection.lol/courtroom/14w14a

U-10 is the first entity players would encounter when traversing Section U, making its debut on room U-010 hence its name. It is so far the slowest of its section, with the quickest currently being its successor, U-40 who players will encounter 30 rooms ahead of them.

U-10 is an Monster that was possibly added in an update succeeding part II of the Entity Extravaganza update along with its section and entities, and like its namesake, U-10 moves in a similar manner to A-10 but is slightly quicker and has a very unique mechanic.

When the entity spawn, it will begin from the lobby and slowly make its way towards the last room, causing moderate screen-shake before finally arriving at its destination. 

Instead of despawning like A-10 when reaching the room, it will check one of the three lockers inside of the room with a random probability before despawning.

It is currently the most basic entity within Section U and is the first runner-type Monster within said section, second being U-40.

U-10 can spawn more commonly after you reach to U-10, but it can spawn even at earlier doors than U-10. It is really rare, so that is why you commonly don't encounter U-10 that often at earlier doors.

Under unfortunate circumstances, if U-10 ends up colliding into the player or discovers the player inside of a locker, it will jumpscare them and forcefully kick them from the game rather than simply killing them. 

When making its way towards its destination it will effuse sounds similar to A-10, though it is vociferously more sped-up and slightly indistinct. Its sound cue when spawning is the same bang sound the aforementioned entity makes, though under the same conditions.

Currently, not much is known more about the entity as it is impossible to encounter it due to players having to traverse all the way to V-5000 to get the keycard to access the section it roams, this is difficult due to ROBLOX crashing beyond V-1250. So far, it is only accessible via exploits.

U-10 appears to have intermixed properties from A-10 and X-10, as it shares similar eyes to A-10 as well as the same toothy mouth, only that it is inconspicuously compressed and frowns rather than smile. The properties it shares with X-10 is its similar cyan color and identically colored glow.

U-40 is currently the second runner-type entity and first backtracking entity players would encounter within Section U. It was possibly added in a minor update succeeding part II of Entity Extravaganza, along with its respective section and its predecessor, U-10. U-40's behaviour is identical to another entity, that being E-200 as both entities remain stationary somewhere in the room before backtracking through the rooms.

U-40 debuts at room U-040 hence its name and will not spawn immediately upon opening the room, appearing a few seconds after opening the room. When it does appear, it will remain idle in front of the door to the next room for three seconds which results in progress being halted momentarily. 

After said seconds, it will quickly make its way backward towards the lobby before its eventual despawn — another thing to consider is that U-40 seems to reverse in its path if it detects a player has left their locker or hasn't hid from it yet, killing them before moving as normal though this may be untrue. It emits a tumultuous static-like sound with barely audible whispers covered by said static.

If the player finds themselves unable to locate a hiding spot or caught off-guard by its sudden appearance, U-40 will jumpscare the player who will be dead for a few seconds. Rather than respawning at the lobby, the entity will automatically teleport the player to THERE ARE CONSEQUENCES FOR YOUR ACTIONS, which serves as Interminable Rooms banland for exploiters and people alike. 

Players shouldn't be worried if they're brought here by U-40, as they can rejoin the game and retry again if they want to.

Not much is known about this entities behaviour as in order to reach its section, players must head all the way to V-5000 and above to find a keycard that will allow them to access the metal doors located in the back of the lobby.  This is quite a difficult feat to accomplish, as ROBLOX begins lagging in rooms above V-950 and seems to crash in those above V-1250 though this varies for different kinds of devices. As of now, this section is only accessible via exploits.

U-40 appears to be a rudimentary drawing of a smiley face that gazes slightly towards the left with eyes that have hollow/white pupils. It mouth seems to be slightly open, revealing the colors red, black and white. It is also accompanied by a bright-red glow with a large radius as well as a minuscule white glow which blends into a pastel-red glow near the intersecting areas of the glow.

U-55 is the third entity players will meet within Section U. It will spawn from the metal door, then rebound a few times. U-55 makes a similar ambience sound to A-100. U-55 appears to be a Winning Smile but green with glitch like effects on both sides, it is also looking slightly left and down.

U-60 is the fourth entity players will meet within Section U. It will spawn at the metal door, go to the last room, and then stay for a few seconds. Then, it will go back a few rooms, go back to the last room and despawn. It looks just like A-60 but grey and very distorted. In-game, it has a glow that switches between yellow, a yellow-green color, green, cyan, blue and pink.

https://objection.lol/courtroom/14w14a