Single Large White Spot on Regal Angel (with pic)

[splix]

Noticed this on my regal this morning. A single large white spot that is protruding. I watched all other fish and didnt see anything. It looks bigger than ich, but may still be. I'm only asking because of it's size, being a single spot on a single fish.
I added a single frag of frog spawn yesterday, it's the only thing that has been added.
Whats your vote, catch him and pull it off of him or just leave him be.

A link to the image which is larger
http://i.imgur.com/kzJ4F5I.jpg

 

[ThRoewer]

Could it be just a pebble that's stuck to its slime coat?

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[Dmorty217]

Could be sand or lymph possibly. Even if the frag brought in ich, it won't be visible on the fish in less than 24 hrs typicacally