Remnants of a fire are ashes.
Ashes
ashes
cinders
Once again its me Kaysh34 in bin weevils it's ashes
ashes
firepitfirefly
The remnants of fire are typically referred to as ashes or embers. Ashes consist of the residue from burned materials, while embers are the hot, glowing remains of a fire that can reignite if not properly extinguished.
A five letter work for a fire starter could be match.
I believe you mean remnants. A remanant is something that remains. It can typically refer to a thing (after the fire, only remnants of the house were left) but can also refer to something intangible like a belief or idea.
* match (strike to make a fire) * mammoth * mink * monk * missle * macaroni * mint
Starting for the Fire - 1896 was released on: USA: November 1896
"Spark of Science: Igniting Curiosity with Fire Starting Experiments"