If I hadn’t looked closely, we would never have seen the little gobies living inside the tangled branches of an Acropora coral, one of hundreds of similar colonies thriving in the calm, clear shallows of Ambon Bay in Indonesia. The perky pair we were watching, like all the members of genus Gobiodon, commonly known as coral gobies, had cute written all over them.

With our faceplates inches away, the pair looked as if they wished that we would just go away. Following a bit of post-dive detective work, we discover that the broad-banded coral gobies — Gobiodon histrio — have quite a story to tell. The little fish are habitat specialists, evolving over the eons to live exclusively within the confines of Acropora.

The fortress of branches — coupled with the gobies’ striking green and orange coloration, advertising their poisonous tissue — keeps most predators at bay.