I got this bubble tip a week ago. Nem has acclimated well and has been fed with reef roids. I am keeping the Nem in an acclimation box for now as my clowns pestered my last BTA to death (started hosting in 5 days!). All is well, but I was curious what this black area on the Nem is? He is from an online store and came with this black area on the disc. The area is about 3 cm long and has no tentacles in that area.