Some samples are transparent, or very difficult to see, therefore, they are stained in order to be seen more clearly and easier to work with.
During eye surgery, the clear layer of the eye is stained to be easily extracted, if it was clear then the surgeon might cut the eye instead of just the layer.
Hope this helps, u might want to search online for more info.
Well, when there is earthquakes, the earthquakes move around most of the fossils into other places and other continents and rivers and oceans, so earthquakes move all the fossils.
