Andromedon

Andromedons are a largely ambiguous species of frail creatures dependant on an atmosphere toxic to most lifeforms.

Overview
Andromedons are first identified serving the Ethereal s as heavily armoured chemical weapon specialists during their occupation of Earth. Andromedons are unable to survive in Earth's atmosphere, and so are confined to a heavily armoured environment suit. The gasses required by the Andromedon to survive are proven to be toxic to Humans, which they take advantage of in their use of acid bombs, likely containing and releasing the gas in their suits. In the event that an Andromedon is killed, their suits will reactivate and behave autonomously. Without the operator, the robotic suit loses functionality to many systems, primarily the Andromedon's weaponry, but will continue to engage the enemy in close-quarters combat.

History
Like the other species subservient to the Ethereals, the Andromedons were conquered and enslaved by them in order to use their genetic material as a component in curing their species' physical degradation. After Earth is subjugated and the ADVENT coalition is established, the Andromedons are used as part of the occupation force.

After XCOM collapsed the ADVENT coalition and drove the Ethereals from Earth, the remaining alien forces were left stranded, but were allowed sanctuary and citizenship on Earth. The Andromedons, due to the toxicity they depend on to live, became isolated from the general populace and resided within specialised sanctuary facilities, maintaining use of their environment suits when venturing outside. However, some Andromedons left the sanctuary to join the ranks of Sacred Coil.