Tick

The Tick is a trinket.

Effects

 * Removes 15% of any enemy's health if they have over 60 HP.
 * Gives Isaac one Red Heart if he enters an uncleared Boss Room.
 * Once picked up, it can't be removed.
 * The Tick can be replaced by Match Stick.
 * The Tick cannot be replaced with the Match Stick if Isaac has or.
 * The Tick can be removed by absorption by, , and Gulp!.
 * The golden version can be removed.

Trivia

 * Being able to replace the Tick with Match Stick is a reference to how one can remove a tick that has latched onto their skin in real life with a heated tip of a match stick; however, removing a tick like this can expose oneself to disease-causing bacteria present in the tick. It is also a feature that was carried over from the original The Binding of Isaac, though it's unclear why it wasn't originally added in Rebirth.
 * The Tick is the only trinket that passively changes Isaac's appearance.
 * The Tick bears similarity to a real-life deer tick.
 * This trinket is used in The Host (challenge #18).