Fat Wood . . . . . .

Finding Fatwood
https://www.instructables.com/id/Finding-Fatwood/

(SNIP) ... Fatwood is also known as lighter wood, pine knot, lighter knot, or heart pine. Fatwood is the resinous remains of a pine tree that has died. When a pine tree dies, either upright or fallen, the sap settles into the heartwood of the branches and trunk. As the tree rots the sap hardens into resin soaked wood, this is the fatwood. ---CONTINUED---

What is Fatwood?
http://www.premierfirewoodcompany.com/building-a-fire/what-is-fatwood/

Fatwood, also known as “pitch pine”, can be found anywhere pine trees grow. Among avid outdoors men, fatwood is known as “natures best fire starter” according to Outdoor Life. It can be quickly ignited and burns long and hot.   ---CONTINUED---

Superesse Straps Fatwood Lanyard
https://www.offgridweb.com/gear/new-superesse-straps-fatwood-lanyard/

  (SNIP) ... Superesse Straps has developed a simple wearable fire-starting lanyard that's based around a chunk of pine fatwood. This resin-impregnated wood is found in the heart of pine stumps and fallen logs, and it burns energetically, making fatwood shavings an excellent tinder source.   ---CONTINUED---

Fatwood: What Is It and Why You Need It
https://urbansurvivalsite.com/fatwood-what-is-it-and-why-you-need-it/

  (SNIP) ...there is another very important aspect to making fire. In fact, it is the very foundation on which a fire is built.

I am talking about tinder. Without a good source of tinder to hold that ember, spark, or flame, starting a fire can be extremely difficult. I have tried many different types of tinder, over the years but there is one that has been my favorite for a long time. Fatwood.  ---CONTINUED---