1. Extraterrestrial Life: This is the most common interpretation, referring to aliens or beings from other planets.

2. Mythical Creatures: These are creatures from folklore and mythology that are often imagined to be supernatural or impossible. Think of dragons, fairies, or unicorns.

3. Spiritual Entities: These could be ghosts, spirits, angels, or other entities that some believe exist outside the realm of our physical world.

4. Unidentified Objects: This is a common term used to describe unidentified aerial phenomena (UAP), often referred to as UFOs.

5. Anything Unfamiliar: In a more abstract sense, "not from this earth" could refer to anything that feels strange, unusual, or outside our normal experience.

To give you a better answer, I need more context. What are you interested in learning about specifically?