Feros
The Prothean Ruin-World
Feros was a dust-choked world buried under Prothean ruins, home to the ExoGeni colony of Zhu's Hope and the ancient plant intelligence called the Thorian, the target of a geth assault in 2183.
Feros was a dust-fouled world whose surface was blanketed almost entirely by Prothean ruins, settled by the ExoGeni Corporation to study those ancient remains. Beneath its colony lay the Thorian, a parasitic plant intelligence, and in 2183 the rogue Spectre Saren Arterius sent a geth force to the world, drawing Commander Shepard into the fight for it.
A world of ruins#
Feros was an old and weathered world whose land mass was blanketed almost entirely by Prothean ruins, with ancient structures covering roughly two-thirds of its surface. Its atmosphere was fouled with dust, and travel across the ground was hampered by crumbled debris piled dozens of meters deep. Evidence suggested the world had once been far colder than in the modern era. Two large moons, the more distant Orcan and the nearer Vardet, circled it.
Zhu's Hope#
The ExoGeni Corporation founded a pilot colony on Feros, named Zhu's Hope, to explore and exploit the vast Prothean ruins that covered the world. The colonists lived among the towering ancient skyscrapers, reaching the corporation's facilities by way of the elevated Prothean Skyway. The settlement was small and exposed, its survival bound up with the strange ruins surrounding it.
The Thorian#
Concealed beneath the colony was the Thorian, an ancient parasitic plant intelligence. The creature exerted a controlling influence over living minds, and by 2183 it had taken hold of most of the colonists at Zhu's Hope, bending them to its will. For reasons that were never made fully clear, Saren Arterius wanted the Thorian destroyed and dispatched a geth force to Feros to do it.
The geth assault#
When the geth attacked, Commander Shepard arrived to investigate and found the colony besieged and its people unnaturally controlled. Shepard fought through the geth occupation of the ExoGeni facility, learning from the corporation's records the truth about the Thorian project and the creature's grip on the colonists. The struggle culminated in a confrontation with the Thorian itself, ending its hold over Feros and the survivors of Zhu's Hope.
Frequently asked questions
- What is Feros in Mass Effect?
- Feros was a dust-fouled world whose surface was blanketed almost entirely by Prothean ruins, with ancient structures covering roughly two-thirds of its land mass. Travel across the ground was hampered by crumbled debris piled dozens of meters deep, and two large moons, Orcan and Vardet, circled it.
- What is Zhu's Hope on Feros?
- Zhu's Hope was a pilot colony founded on Feros by the ExoGeni Corporation to explore and exploit the vast Prothean ruins covering the world. The colonists lived among the towering ancient skyscrapers and reached the corporation's facilities by way of the elevated Prothean Skyway.
- What is the Thorian on Feros?
- The Thorian was an ancient parasitic plant intelligence concealed beneath the colony on Feros. It exerted a controlling influence over living minds, and by 2183 it had taken hold of most of the colonists at Zhu's Hope, bending them to its will.
- Why did Saren attack Feros?
- For reasons that were never made fully clear, the rogue Spectre Saren Arterius wanted the Thorian destroyed and dispatched a geth force to Feros to do it. Commander Shepard arrived to investigate, fought through the geth occupation of the ExoGeni facility, and confronted the Thorian, ending its hold over Feros and the survivors of Zhu's Hope.
Gallery

Images via Mass Effect Wiki
Sources
- WikiFeros — Mass Effect Wiki entry
- WikiFeros: The Thorian — Mass Effect Wiki entry
Spotted a factual error or a primary source we missed? Email a correction. Every flagged claim gets reviewed.
Related entries
Prothean
The Protheans were an ancient race who ruled a galaxy-wide empire before mysteriously vanishing some fifty thousand years ago, harvested by the Reapers. Long credited with building the Citadel and mass relays, they secretly nurtured younger species, leaving ruins and technology that shaped the modern galaxy.
Thorian
The Thorian, also called Species 37, was an ancient sentient plant on Feros, at least fifty thousand years old. It controlled the minds of those who inhaled its spores, turning them into thralls, and held an entire colony in its grip until Commander Shepard destroyed it in 2183.
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Commander Shepard was a Systems Alliance N7 marine who became the first human Spectre, exposed the rogue agent Saren Arterius, and led the galaxy's resistance against the Reapers. Shepard's gender, history, and many of the choices that shaped the war were never fixed, and the final fate of the cycle turned on the Commander's own decisions.
Geth
The geth were a race of networked artificial intelligences built by the quarians as laborers. When they gained sentience and questioned their makers, the quarians tried to exterminate them; the geth won the resulting Morning War and withdrew behind the Perseus Veil to build their own future.
Saren Arterius
Saren Arterius was the longest-serving turian Spectre of the Citadel Council and a feared agent of galactic order, until he fell under the influence of the Reaper Sovereign. As Sovereign's indoctrinated agent he led the geth against the Citadel, and his defeat fell to Commander Shepard.
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Spectres were agents entrusted by the Citadel Council with extraordinary authority, including the power of life and death over the galaxy's people. Operating outside the law to preserve galactic stability, they were drawn from the finest operatives of the Council races and answered to no one but the Council itself.
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Thorian
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