Horseguard

Horseguards are aquatic monsters based on sea horses. Its name, "Horseguard", is derived from "sea horse", an underwater creature with a horse-like head. It is also derived from "coast guard", a military force employed to watch over maritime traffic, referencing the monster's military theme.

Biology
Horseguards have long, slender bodies. They have tough, black skins on their head and tail, while their abdomens have a strange camouflage pattern. They have long, ridged mouths which they use to eat. Horseguard gills can be found below their green eyes. Flat green spines line their head and tail, while similar camouflaged spines line the back of their abdomens. Horseguard tails curl inwards, and they use this tail to move.

Large Horseguard colonies can be found in seas, particularly at reef areas. They feed on algae and microplankton, and are notoriously heavy eaters.

Behavior and abilities
Horseguard units are among the most organized colonies under the sea. Though they are prey to many underwater predators, Horseguard units are relatively safe due to their ability to rally themselves against threats. During nightfall, half of the Horseguards in the colony go to sleep while the other stand guard, alternating every hour.

Horseguards are capable of performing the following abilities.

Rally. The Horseguard releases a bellowing call that only Horseguard can hear. Nearby Horseguard within earshot would rush to the Horseguard's aid. A Horseguard unit's typical formation is a spherical one, with either the oldest or the rallying Horseguard in the center.

Takedown. The Merc rotates forward in a 90 degree angle before winding back and brutally tackling a target, attempting to knock it back. The spines on the Merc's head helps to improve the damage dealt.

Underwater buckshot. The Merc inhales a large amount of water into its mouth before firing a pressurized blast in a cone, attempting to stun the targets hit. This ability works best from close range but can still be potent from long range.