A good case study may be the octopus. They are highly intelligent organisms and a strong argument could be made they have "mind". A quick search [0] shows some evidence they communicate via "posturing and changing color"--is this language? How does one prove an individual has mind?
Regarding the definition of "mind" the mirror test seems very relevant but does "mind exist without the sense of self"? What about emergent phenomena amongst highly social animal groupings...?
Edit: I must be in the "mind" came first camp but in this case mind === consciousness but mind != consciousness
[0] https://www.livescience.com/53514-octopuses-lead-social-live...