A joke has been spreading across the internet lately, and it goes something like this: humanity’s ultimate destiny isn’t to become cyborgs or upload our consciousness to the cloud. No, according to viral memes, we’re all eventually going to turn into crabs. And here’s the strange part: there’s actually some real science behind the humor.

At a small natural history museum on the English coast, staff members report that visitors now arrive daily with the same question. They want to know if humans really will sprout claws and start scuttling sideways. The museum’s director admits he’s struggled to provide people with a satisfying answer. However, evolutionary biologists believe they can explain why the internet has latched onto crabs as evolution’s ultimate form.

The answer lies in something called carcinisation—the scientific term for becoming more crab-like. Remarkably, nature has invented the crab body plan at least five separate times over millions of years. Different groups of crustaceans, having faced similar challenges in their environments, independently evolved the same solution: a rounded shell and that distinctive sideways walk.

To understand why this keeps happening, you need to know that crabs belong to a larger family called decapods, meaning ten-footed creatures. This group includes lobsters and shrimp, which possess long, cylindrical bodies with muscular tails. Those tails enable them to snap backwards at high speed and burrow into the seafloor.

True crabs, however, inhabit a different world. They occupy shallow coastal waters and rocky shorelines, environments in which a different body plan proves more advantageous. Crabs have compressed abdomens tucked underneath a flattened, rounded shell, a design that presents fewer vulnerable spots for predators to grab and allows their legs to move sideways, facilitating rapid escape into narrow crevices.

Here’s where it gets interesting. At least four other groups of creatures have gradually transformed themselves to resemble crabs. Sponge crabs did it. Porcelain crabs did it. King crabs did it. Even something called the Australian hairy stone crab did it. These are what scientists call imposter crabs—creatures that evolved their crab-like appearance independently by tucking their tails underneath their bodies over millions of years.

What this reveals is that crabs aren’t actually a single biological group; rather, they’re a collection of different creatures that evolution has shaped to look remarkably similar. Researchers explain that these imposter crabs sacrifice their muscular abdomen in exchange for superior armor and mobility.

This process exemplifies convergent evolution—the phenomenon whereby groups that aren’t closely related come to look similar without sharing a common ancestor that also possessed those features. Evolution keeps discovering the same answer in different lineages and different places, a testament to the effectiveness of certain body plans.

Consider birds and bats. Both developed wings because they face similar environmental challenges, despite being completely different species on separate branches of the evolutionary tree. The same principle applies to crabs, which converge on this body plan because it represents an efficient solution to a specific set of physical problems.

A compact, broad, armored body with a tucked abdomen addresses multiple challenges simultaneously. It provides better defense against predators. It works well for living in crevices. It handles wave-swept environments more effectively. It enables sideways agility. And it offers broad protection from above—a comprehensive suite of advantages that explains its repeated emergence.

Experts say it’s been amusing to watch the internet debate unfold, but they want to be clear: the answer is still no. Humans will not evolve into crabs. Had we been decapods rather than vertebrates, we might have stood a chance, but the convergent evolution of crabs has occurred approximately five times in Earth’s history exclusively within the group of decapods. We’re vertebrates on an entirely different branch of the evolutionary tree, making such a transformation biologically impossible.

Still, there’s something deeply appealing about the idea. Perhaps it’s because the crab represents a kind of evolutionary perfection within its ecological niche. Nature, confronted with the problem of surviving in shallow coastal waters, kept arriving at the same solution. Five separate times, different creatures discovered that becoming more crab-like was the answer—a remarkable convergence that speaks to the power of natural selection.

So while you won’t be growing claws anytime soon, the next time you see a crab scuttling sideways on a beach, you’re looking at one of evolution’s most successful designs—a body plan so effective that nature can’t stop reinventing it.