The featured creatures of Ahch-To have befriended Luke Skywalker during his residency as a Jedi recluse. Lukes little friends are avian in nature. Skellig Michael is where the island of Ahch-To was first glimpsed in Star Wars: The Force Awakens. The new creatures from Episode VIII are actually designed after the puffins that inhabit the area in our real world. So there should be little question if the design actually fits the environment.
Rumor has it the creatures have razor sharp teeth and are a mixture of the terrifying and the adorable. Theyre sort of like a bird mixed with a Gremlin. Someone once said it was like the Star Wars version of a Furby, but the look and feel is so Star Wars they loved it. Basically combine a puffin, a Furby, and Star Wars it up and you have yourself an idea of what this creature is. Theyre tiny, maybe fifteen inches tall or so. I was apprehensive when I first heard Furby, but no one speaking of the design has anything bad to say about it. In fact, those that have seen the tiny puppets on set are overjoyed by their presence in the film.
The other rumor worth noting is that the puffin that personally has screen time with Skywalker sees himself as a protector of the island(s) on Ahch-To. Luke Skywalker has permission to be there while Rey does not. Rey has a sequence on Ahch-To where she fights a rather large sea monster (we have also heard she wears a black cloak during this sequence over the costume we described before). It has been suggested but not confirmed that Reys besting of the sea monster grants her permission to be at the sacred location by the puffins. However, the sequences could be totally unrelated.