Claro is known for having internal voids like this. Usually you will not see them until it is too late. When approaching the final thickness I usually stop the lathe periodically and feel the surface to check for soft spots.I have extra blanks if you need one. The demo piece for the vase class was from this bin at Woodcraft and my partner picked up several after visiting Woodcraft back in October.
Thanks for the offer, @David The second blank I got is still intact, but I might ping you if that one also turns out to be the Swiss cheese subspecies of walnut.
Here’s what was hiding in the blanks I got – two turned teardrop boxes. The shorter one was from the blank I posted upthread, full of voids. The taller one is closer to what I was trying to accomplish: