i'm a little late to the post.
but i had one stuck in my phone. just got it out; so proven!
unfortunately took me about five minutes; basically take an eyeglass screwdriver and scratch at it; i had to do 1/6 of my ball before it finally came out; (in one large piece; and dusty debris); not sure if it varies; but my screwdriver is extremely sharp; I can create a scratch on my hardwood type of sharp.
i've tried the sewing needle, toothpick, safety pin etc; not sharp enough; and flimsy (hard to get a good grip)