"things" growing on my aro's back....need help IDing and Solving

sorry for the blurry picture..can't get a good picture of my aro....

anyway, from the picture..you can see lots of "things" growing on its back area....only happened this tuesday... i have no idea what that "things" are. hence i have no idea on where to find a solution for it...

any bros here encounter such "things" before?.... can recommand solutions to help my aro?...