Time lapse of slime molds and various mushrooms growing:
Slime molds are crazy organisms. They live animal-like lives for much of the time, but will eventually "settle down" when it's mated (if you can even call it that) and then release spores as if they were fungi. Some experts have argued that slime molds should be their own kingdom since they are so unique.
It's a good illustration of how science is a construct of our own species. We do our best to make observations and organize the universe into distinct categories. Sometimes, however, there are things that don't fit cleanly into our categories. These often lead to debates between groups of scientists, who eventually reach a general consensus based upon the best information available. Often when new information is discovered, we learn we had it backwards or even find out we really had no clue what was going on in the first place. All of which is OK, since it's all progress.