So glad you asked!
It's a project started in Australia by two crocheting sisters seeking to call attention to the destruction of the Great Barrier Reef.
Interestingly, there's a mathematical angle to all this. I will likely not get this entirely right, but basically for some time mathematicians denied there was a hyperbolic function until Mr Vincenzo Riccati and Johann Heinrich Lambert came up with it in 1760. This despite the fact that many coral grow hyperbolically, so there were examples right under their nose (or toes).
And you can crochet a hyperbolic function by simply creating a chain and doubling it for every stitch--example below:
It was a powerful visual and experience to remind me you can start with something very simple--a single chain stitch. Then do something very simple--double it. And if you continue to add these simple building blocks, you can create something of amazing complexity--perhaps even beauty. Just think about the single cell dividing and dividing and what remarkable organism it can come up with!
And for those of you may be wondering how this relates to hyperbole? I figure it's whatever it is, just double it!