Dead pets have only been seen in the magic bean dimension when someone has a grave stone up there and a dead friendly creature they made, they have been seen in the normal dimension when someone has a gravestone there too, little is known about these creatures but they have a blue version of the basic yellow smiley face emoji above a friendly creature and a ring above the smiling head emoji, they appear In front of the gravestone and talk in glitchy captions, these dead pets look like spirits found in the over world
(here the one who edited this, just gotta say it happened to me that I had a gravestone in the normal dimension and one of my pets had died, after some days it appeared infront of the gravestone just like said so, hope you don't mind)