they are most likely remnants of its external gills. i have a weeksii that is about 7" now and she still got them. one side is a little longer than the other too. i have read others post about external gills on some of their polys and how long they are visable and i guess it depends on the individual poly. i have seen gills on 5" dels and no gills on 2.5" dels. i think they look cool. they weeksii's head already looks the best out of all the upper jaws in my opinion. (just so wide and cute) BIG mouth too!