Website works without critical files... Am I going mad?

Website works without critical files... Am I going mad?

In a nutshell I'm trying to add in a custom Instagram API feature into my
website so I injected some code into "index" and renamed it from
"index.html" to "index.php" since the code I injected was php code.
So ok, I wanted to see how my code was doing. I opened my website's
homepage, and.... nothing
after a half hour of trial and error I completely deleted index.php but...
what the hell... my website works without the homepage now:
www.cinicraft.com
so all the fancy bells and whistles you see once you load up my website
come from index.html WHICH I renamed to index.php (then I saw that my php
code had no effect) so I deleted index.php entirely but wtf... there's no
index in the root dir of my ftp server... how does my website still work
without the index.html and index.php?????