• Palaeontology: This is like being a detective for ancient life! It helps us track down when the first living cells and the LUCA (Last Universal Common Ancestor) might have existed.

• Rocks from 3.5 to 3.0 billion years ago (Gya): Imagine a rock as old as 3.5 billion years! Some of these rocks have fossil-like structures that hint they might have living organisms inside them. But, it's like a mystery novel - some alternative explanations are also there!

  Real-world Example: The rocks in Western Australia's Strelley Pool Formation. They have something called stromatolites that are like ancient selfies of cyanobacteria!

• Stromatolites: Picture a bunch of tiny bacteria on a beach vacation, laying on mats, trapping sand, and slowly making rocky mounds over thousands of years. That's a stromatolite! It's one of the strongest pieces of evidence for early life, dating back to 3.42 Gya.

Carbon Isotope Ratios: Now, this is like a secret code! Carbon from living organisms has a specific 13C/12C ratio. If we find this in ancient rocks, it's a clue they might contain life's remnants.

Real-world Example: Banded iron rocks in Akila and Isua, Greenland showing this ratio. Think of these rocks as ancient messages in a bottle, possibly pushing life's origin back to 3.70 to 3.85 Gya.

• Metamorphosed Rocks: Sometimes rocks undergo a serious makeover through heat and pressure, and the fossils are lost. It's like baking a cake and losing the individual ingredients!

• Zircon Particles: These are like the tough survivors of rock erosion, and they have been found in younger rocks dating from 4.1 Gya in Jack Hills, Western Australia. These particles might hold secrets about early life, but it's not solid proof yet.