Eh, what fireflies can do is kinda the base level of the bioluminescence 'skill' of the evolutionary tech tree.

https://gizmodo.com/glowing-deep-sea-squid-have-a-complex-form-of-communica-1842472534

https://youtube.com/watch?v=DE89YY7zCio

Humboldt squid skin is bioluminiscent, but roughly akin to a flexible lcd or oled screen, with many different 'pixels' capable of being set specifically.

They likely have the ability to communicate by basically displaying different patterns of different colors and brightnesses and translucency, sorta like a human walking around with a sandwich board made of lcd screens, which they can control with a phone app.

They may very well have an entire language they can convey via sequenced or at least specific patterns.

Note: No clue if you can actually trace bioluminescence in fireflies and certain cephalopods to the same common ancestor or if its completely different, independent evolutionary occurances, but my point is there are certainly more and less complex and utility granting forms of bioluminescence.

"I cast 200 μg Luciferin."

[Dice noises]

"Nat 15. Your abdomen glows and dims slowly and rhythmically."

Nah, it legit is, though. Just because someone or most someones understand how something happens doesn't mean it isn't magic anymore. It just means that we have a hard magic system. We understand our magic so well that we've stopped seeing it as magical, but if you take a step back and take a look at the big picture it becomes clear that the world is magical, and everything around us is this amazing, often confusing, incredible tapestry of Wonder and awe. The world has just ground us down so much that we feel like wonder is strictly for children, that we're not allowed to feel wonder anymore. Embrace the magic. Even if you know how it works.

Spelling it without help is also magic, so I hear ya.

Magic exists but we call it science

Hell ya. Real magic is the feelings we felt along the way. Swimming in bioluminescent waters is one of my favorite life experiences

Fuckin bio-lights how do they work

Humans are bioluminescent, too! But it's too dim for anything to actually be able to see, so it's no fun.

The definition of magic I go by is "affecting consciousness in accordance with will", and when you're going to watch fireflies with the thought in mind to appreciate them aesthetically, then yes, they are actual magic.

https://norse-mythology.org/concepts/magic/

Magic produces change by working directly with consciousness. Its effects often spill over into the physical world, but this occurs only indirectly. This is, in an important sense, the exact opposite of what modern science does. Science causes changes in the physical world in accordance with the “laws” of the physical world. Magic and science not only work by different means; they also work toward different ends, and, in fact, this difference in ends accounts for the difference in means. This is why practitioners of magic don’t conduct laboratory experiments, and why scientists don’t intone chants before altars inscribed with emotionally powerful symbols. The apologists for the conventions of our own age often claim that magic is a “primitive,” immature groping toward science, and now that science has arrived, magic is obsolete. But science and magic are different enterprises altogether. Neither can entirely supersede the other. Indeed, as will be discussed below, magic is as alive and well in the modern world as it’s ever been – it’s just been brilliantly disguised