An Egg Timer is a common item found throughout the ship in Monstrum that when activated by the player will begin a 30 second countdown, at the end of which it will loudly ring 3 times, attracting the monster to its location.
Egg Timers can be dropped while in their active state, making them a highly effective lure.
Egg Timers cannot countdown while in your inventory unless it is the currently selected item, and will reset if the player selects a different item.
An egg timer will also reset when it is picked up.
Egg Timers can be thought of as the safer, but less reliable version of radios in that they can be planted in a location the player wants the monster to go, while allowing the player ample time to find a place to hide. The trade off is that radios can be made to emit noise instantly, and will continuously emit noise until they are turned off or destroyed, which ensures that the monster will go towards it (where as an egg timer may stop ringing too soon, and the monster will alter its course).
Although all three monsters will seek out a ringing egg timer, the Hunter's reaction is especially swift in that it will immediately emerge from a nearby vent in the same manner as if an alarm had been set off (assuming it wasn't already roaming the halls).
Egg Timers can be found practically anywhere, but are more common in the Upper Decks of the ship, particularly the Kitchen.
The egg timer's knob and dial flip vertically when activated. This may be considered a graphical bug.
The remaining time of the 30 second countdown can be seen on the dial of the egg timer as it is fully animated (though only when the player holds it as the selected item).
If an egg timer stops ringing before the monster reaches it, such as when it is on the other side of a door, they will not destroy it, meaning it can be reused (unlike a radio, which will not stop making noise).