Protuberance is a funny word that means a thing that protrudes or “sticks out” from something else. For small meteoroids, 90% of the mass is lost to ablation as they come through the Earth’s atmosphere. If a stony meteoroid had a protuberance in space, the protuberance would be the first thing to break off or ablate away as the meteoroid passes through Earth’s atmosphere.
If you have a rock with a protuberance or other features that sticks out in positive relief, then it is not a meteorite.
All of the photos below were sent to me by persons asking if the object was a meteorite. All have protuberances so none is a meteorite. Also, none of them has a fusion crust.
Botryoidal hematite often has protuberances.Pebbles conglomerates are sedimentary rocks in which, often, the rounded pebble clasts are harder than the matrix and thus stick out from the matrix. Except for the reddish one on the lower left, the the whitish clast are largely quartz, a very hard mineral.All of these rocks have features that stand out in “positive relief.” The 3 rocks at the top are some kind of concretions, I do not know how these form, but they must be common because I have been sent several photos like this.General guideline: If it looks like a rabbit, then it is not a meteorite. The person who sent me this photo said “This meteorite is definitely a rarity and something to be studied for sure.” On the basis of the color I suspect that it is composed mainly of hematite (= not rare). There is no fusion crust. If there was, then the clasts would not be so prominent.
