Yes, that is The quintessential look of BJD.
Seeing the tissue recession right up to the jelly makes it even more clear.
First up is to get that OUT. shut off all of the flow in your tank, I usually reach in with a Ziploc bag over my hand and cover the coral in it before bringing it out. You don't want that to blow off while you move it.
Frag the affected head off of the greater colony.
Do you have ciprofloxacin on hand?
Look at the flash below the heads of all of your other Euphyllia. Every BJD affected coral I've seen has Started with quick tissue recession.
I've documented a recent run in with BJD where I was able to save one of three heads and had no other transmission across the tank.
Post in thread 'Finding Sauce (a lot of tanks in a little time) 180G mixed reef'
https://www.reef2reef.com/threads/f...tle-time-180g-mixed-reef.807281/post-10363761