I like to know what is the math behind the outlines of these boards
https://www.boardgamegeek.com/image/4383021/spirit-island
https://www.boardgamegeek.com/image/4880004/spirit-island
https://www.boardgamegeek.com/image/2706606/spirit-island
https://www.boardgamegeek.com/image/3692997/spirit-island
https://www.boardgamegeek.com/image/4013584/spirit-island
I wonder how to come up with these exact shape and how to express this in a formula. The maker of the Boards used the term tessellation and mentioned that it was initial based on a hex map. I like how they fit nicely and still give the impression of uniqueness. Is there anything else interesting (from an mathematicians point of view) about these?