Activity for unfa
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Question | — |
How could an alien mine exist under a planet's surface without humans detecting it from above? Imagine a human observation and research facility being built on a planet in a distant solar system. How could an alien colony exist beneath the planet's surface, staying completely invisible to humans on the ground? Let's say that aliens have a portal technology allowing them to travel from within ... (more) |
— | over 6 years ago |