With the recent changes to the Art making so yordles now having 4 fingers Amumu is confirmed to be also a yordle, Though I don't remember seeing his art in the -patch notes seeing it now in the client it is all but confirmed.
Sharjo7 votesI guess this means that Ivern, Renekton, Blitzcrank and Twitch are yordles too then.
Glad that's cleared up.
ForgottenLuck4 votesEhh I chose to believe the unique biology that yordles possess with the short figure, somewhat humanoid, four fingers. Plus the fact that the lore page leads us to believe he is either human or yordle with not really telling us which. I for one am glad to finally know what he is. As for the others well I will leave Riot to reveal that in their next reworks.
Sharjo4 votesWell I do not choose to believe, but in fact know that humans can lose digits or not even be born with a full set of digits.
http://i.imgur.com/OE7Cfu2.jpg
So I'd say it's still up in the air.
ForgottenLuck3 votesOligodactyly, oh yes it is possible but it is a rare medical condition in all honestly, it is even rarer medical condition than to be born with extra fingers, Polydactyly, yet you do bring an interesting topic of medical anomalies into the world of Runeterra. I mean in a world with 
, 
, 
, I am not one to through it out but would find it a bit strange in there also being magic in the world to cure it.
It could also be that the ritual for his mummification had a ritual to cut his finger like ancient Egypt had with taking the brain and storing it in a jar, yet the only one I have to parallel this theory is Azir, and though he was not mummified he still posses all 5 fingers.
LostFr0st1 votesD:<
Dynikus1 votesthe shop keeper on the howling abyss has always called him a yordle. it was heavily implied before, but I guess the 4 finger thing confirms it.
ForgottenLuck1 votesDebatable if he was as heavily implied when the own lore page of his wants to keep it a secret. It specifically leaves it open to be or human or yordle. With how even in runterra no one can seem to be sure what he is I trust the fact he now has a yordle biology than what runeterrens say.
GreenLore1 votesThats because when the shopkeeper was introduces Amumu was a yordle. Only when his new lore came out it became questionable if he was a yordle or not and even then it is said that some people think he is a yordle,even though it isn't clear.
so yeah the quote of greyor on the howling abyss is rather outdated and could still be seen as him simply thinking that Amumu is a yordle.
Moonboy651 votesAmumu already had 4 fingers on all of his splashes, this was just a process for fixing Yordle splashes who had 4 fingers
