Beginner Gardening: This is a WEIRD bug/bugs?, 1 by DaleP6

DaleP6 wrote:
This is as close up as I can get. Bear with me while I try to describe this. On the Christmas berry leaf there are small black "dashes" for lack of a better word RIGHT on the leaf's edge. On the underside of the leaf below the black "dash" came a little pocket and from that came a small white fluffy thing that I do not know if it was alive or not. The white thing has stuck there like glue so I am led to believe it might have been an encasement. The black "dash" looks like it opened...and whatever came out came out between the top and bottom of the leaf as after a day or so the "dash" seemed to almost be a slit...RIGHT on the edge. Any ideas? This was the only leaf with this on it. Very strange...plus they were evenly spaced, four on each side!