I have two coticules yellow. One selected bout from in visable edge which has a black slate base which is normal. The other one is a small kosher from rob of ardennes the other coti is also from ardennes.The kosher has a blue purple base and whilst laping the corners and sides i noticed purple slurry so i laped the under neath and it is relaesing purple slurry so i can only persume it could bbw. i have copared it to my actual bbw that have and it does'nt seem the same in texture. it looks exactly the same as the yellow coticule but a differant colour when the light reflects the kosher you can see like little speckles and the base also purple with little speckles.