The fact is they're obviously looking at other tails for some of the designs they have put out. ie, the lotus tail, the blue tang tail. and then there are the obvious things like their moon pool tail (I think most of us recognise a mako tail when we see one) and the Electric neon merman from their instagram is obviously copied the male tail from the same series.

and just to be knitpicky you look at the fluke shapes and some of them are very similar of the standard merbellas fluke...I know fluke shape is a hard one to fault because there are only so many ways to go with it, and the fact that the well know tail makers keep pumping them out means the pool is getting smaller.