A species of fungi known as Golloriee is a fairly uncommon creature I've come up with. Its origins are certainly very unnatural, but have been shrouded in folklore over time, they say the crystals were born from a dead god, can you believe that?(but it does explain the magical energy, and the occasional..sentience, these little crystals have.)
The fungi grow in damp areas, like swamps, underground caves, pipes and sewers that haven't been tended to, etc. and they need to latch onto a host animal to reproduce, eating the animals flesh and growing crystal stalks in its place like a mold, and spreading spores from those stalks, or stabbing into a nearby animal and starting the process all over again! so I suppose that's an evolutionary reason for growing into sharp crystal shapes.
The older the stalks, (as in hundreds of years,) the more likely they are to start thinking, but this is pretty useless unless something is there to teach them stuff. these smart spores usually target a hosts' brain instead of their organs, and grow within it, attaching to the neurons and taking command! how scary is that? good thing all those ones are underground.
Anyway, how plausible is this species? How much would I have to use the "iT's MaGiC" excuse with?