n medium aberration 

Perception +9; darkvision

Skills Athletics +12, Deception +8

Str +4 Dex +1 Con +3 Int +0 Wis +1 Cha +0

AC  20; Fort +11, Ref +9, Will +9

HP 75

Adhesive Any creature that touches the mimic (usually from a fist Strike, the mimic's pseudopod, or a Grapple or Shove) must succeed at a DC 23 Reflex save or gain the grabbed condition. The DC to Escape is 23. A melee or thrown weapon that hits the mimic sticks to it. A character can spend an action to attempt a DC 23 Athletics check, removing the weapon on a success. The adhesive dissolves 1 minute after the mimic dies.

Object Lesson [R] If a creature touches the mimic while the mimic is transformed into an object, the mimic can spend its reaction to use its adhesive with no saving throw. The mimic then makes a pseudopod Strike. Object Lesson can't be used again until the mimic escapes and takes on a new disguise.

Speed 10 feet

Melee [>] pseudopod +14, Damage 2d8 + 4 bludgeoning plus adhesive

Mimic Object [>] (concentrate) The mimic assumes the shape of any Medium object. This alters its visual appearance but not its size. It takes a DC 28 Perception check to tell the object is a creature.

Beginner Box, page 71.