There are bowls with strange protrusions at the bottom which makes it very hard to access the last bits.
I had to check what they are for and the answer was "Slow Feeder" but haven't seen this very pattern.
Ahaa! "Outward Hound Fun Feeder Slo Bowl"
This one is the "Slow Feed Bowl":
And here is the owner - sometimes needs to be slowed down...: