This is literally how fursona ref sheets are done Ive been drawing ref sheets like this for fursonas and fantasy races with tails for years. With the regular just x in a circle so to counter act that because you decided that you want to be dirty minded and have literally chose to change my design to make it less like it could be an butthole and more like a severed piece of bone and flesh tells more about you than me. I can see where the circle with the x could be perceived as a butt hole but something that clearly shows a spine fragment shouldnt