Can someone please help identify whats growing out of my walls

Saw something on the wall the other day, thought it was somethjng that just flew in from outside and i wiped it with a cloth. The very next day it was back again. Seems to be growing extremely fast--about half an inch in all directions in just one day. Looks like spores/dirt when taken off wall. I will try to post a pic. My landlord is horrible, so i want to try to get as much info an possible before i contact him this week because i know he will do anything to not have to spend a dime.

Will try to post a pic

Thank you

http://tinypic.com/r/2zydjyg/9