Mortar Synth

The Mortar Synth is an assumed aerial Synth seen being transported on a conveyor belt in the Citadel prior to its destruction.

Overview
The Mortar Snyth consists of a fleshy, triangular body with what appears to be some sort of a cannon located on the Synth's back. The Synth's front end features many spiked protrusions and various mechanical systems.

Like the Crab Synth, the Mortar Synth is never encountered in an actual combat situation, but are described as being self-replicating, part-replacing creatures that they serve as the backbone of the Combine's armies.

Trivia

 * When a mortar synth is approached during play and interacted with the USE key, the entity's current animation will freeze and continue moving by frame when it is shot. Its animation would resume when the USE key is pressed again.
 * Mortar Synths bear some resemblance to the Manta Rays from the original Half-Life.
 * In Garry's mod, there is a full-working Mortar Synth and it fires a reddish laser similiar to the stalkers that does a considerable amount of damage. When it dies, it explodes.