Repost an posts from 8/2 chan that stuck with you. Preferably with an archive link, but that isn't obligatory.
Starting off on my end with two posts about fungal extinctions. I've a passing interest in fungi and realizing they might be 
still responsible for mammalian dominance as the larger mammals is astounding. Before this I was aware of pathogen fungi as athelete's foot, ergot, and black mold had no idea they could be have been this dangerous.
https://desuarchive.org/an/thread/4153806/#4158990
https://desuarchive.org/an/thread/4404183/#4406478
Closely related is the Sacchalina and Wolbachia among crustaceans. These aren't fungi but rather a 
barnacle and bacteria respectively, but effectively castrate and feminize afflicted male crabs, as well sterilizing female crabs. 
Sacchalina itself is fascinating, this is a barnacle, which starts its life motile, before finding a fitting host, losing the majority of its biomass and size and living entirely as a parasite within its host. Evolution does not necessarily favor greater complexity but rather whichever organism best succeeds in passing its genes to future generations. In this case an endoparasite.
https://desuarchive.org/an/thread/4859860/