Shaelmaar

Szarlej is creature which was part of the early design for the third game, but was dropped later.

The Witcher 3: Wild Hunt
Szarlejs were supossed to appear in base game during its development in 2013 - 2014 but they were quickly removed and we would not know of all of this if not of leaked materials.

Informations from leaked materials
''Vile and cruel monster living in the mines. He was getting rid of miners by collapsing mine ceilings and flooding tunnels.''
 * Role in the group: Individual
 * Preferred behavior: charge from a distance
 * Special attacks and actions:
 * Strong attacks - his attacks are slow paced but deal high damage.
 * Charge  - the creature jumps and turns into a rolling “rock” (animation). It charges, the target is knocked down if hit. The attack deals high damage. If the creature hits a wall or other solid obstacle, it is stunned for a moment.
 * Charge can be dodged. Blocking with Quen saves from damage but not from the knockdown effect. Charge cannot be parried.
 * Throw a rock (mud vomit) - the creature can throw rocks when in crouching state (see below). It opens it’s defence for a while and throws a small rock (using projectile mechanics). Then it closes again. When player manages to hit the creatures when it tries to throw, it will exit the crouching state.
 * Quake - special action used only on dedicated arenas (when in proximity of “stalactite entities”). Monster hits the ground with a powerful blow and causes some rocks and stalactites to fall from the arena (cave) ceiling. Each rock is a rigid body, that deals physical calculated damage on hit.

Defence

 * Crouch - the creature can crouch and turn into a “rock” (animation). It’s invulnerable for a specified time or until forced to “open”. It can be forced to get out from the crouching state, when player hits it in the moment of the Throw a rock action.