It is very realistically designed, having black edges, a coal-like surface, and has a highlighted area will be affected depending on the position where the luminosity comes from.
The Lump of Coal is also comparable to the Roblox gear, Sparkle Time Lump of Coal.
If the Lump of Coal has been put inside the Volcano for about 10-15 minutes, it will ignite, revealing an orange rock, with a highlight of yellow in the middle, and flame particles blowing out of the coal while it's on fire. The longer the coal stays inside the Volcano, the longer it will be on fire. The flaming version will save to your plot if you keep it at your plot. However, it will cool down in an amount of time and becomes black again.