Annihilation ending explained: The Shimmer's purpose no one saw but Lena and the present it left for her

The best thing about Alex Garland's 2018 film Annihilation is how silently it makes the environment tell us it's all about refractions. In some ways, it's dark, yet it is perfectly colorful to the edge so we don't deem it psychedelic like O'Dessa's dystopian world.

At the heart of it is the Shimmer, a phenomenon, an influence, or just an alien entity that doesn't know it's experimenting all the time. To understand it the best, a meteorite-like thing crash-landed on earth and it spread like radiation, similar to what happened after the Chernobyl disaster.

To put it simply, it breaks down a matter (read that as refraction) and then creates something new out of that matter's image. We can say that's the purpose of it but it doesn't know this, as it's not a conscious being doing this consciously. No one understands this better than the film's lead, Lena, who Natalie Portman portrays.

Annihilation's title is the cue to understand the Shimmer

The film does demand some proper attention from the audience to understand itself but it also gives the cue in its title, Annihilation. The Shimmer is a scientist who likes to, pay attention here, 'annihilate' things and pull them apart while also injecting elements of other matter that comes in contact with it to give us something new.

It's like Demolition's Jake Gyllenhaal. He annihilates things, but then he isn't trying to pull them together to create something new, although he wants to as he is acting on this advice:

"Repairing the human heart is like repairing an automobile. You have to take everything apart, examine everything, then you can put it all back together."

It's happening all the time in the film in different ways with the all-female squad. A mutated bear mimics Cassie's (Tuva Novotny) voice instead of growling after killing her, Josie (Tessa Thompson) turning into a flowery tree, and Lena's clone shaping in front of her eyes.

This last instance best explains the Shimmer in Annihilation. You see Ventress (Jennifer Jason Leigh) disintegrating into a mandelbulb-like thing. Think of it like a blob-like earth with gravity that attracts everything. Only that it's not Earth; it's Ventress, or, well, whatever remains of her.

When Lena goes closer to it, she has this drop of blood sitting near her right eye, which is pulled by this gravity. Now this mandlebulb, or disintegrated Ventress, is infused by Lena's blood, giving it a shape, a clone of Lena, which mimics her movement.

The Shimmer is burnt to ashes but it left a present for Lena

Maybe the Shimmer isn't doing what it's doing in Annihilation on purpose, but the antagonist and this film demands its demise, or everything will be lost to its experiment. So what Lena does is hand her clone a phosphorus grenade and runs outside this lighthouse, which is like the core of the Shimmer. There's also a burnt corpse sitting there.

As we know it, the Shimmer disintegrates and then reintegrates but also mimics everything it touches, so it mimics fire and burns itself down to ashes. But before that, Lena finds something that's devastating for her.

She sees her husband, Kane, in the footage burning himself with a phosphorus grenade, revealing that it's the corpse of her husband. But he is talking to someone before acting, to whom he says,

"If you ever get out of here, you find Lena."

Turns out, he is talking to his clone. We see Kane in the beginning of Annihilation, and now we know that he was this clone, a present Shimmer left to Lena. At least that's what we can say as she now knows the gruesome fate of her husband. They do embrace each other at the end, though it feels weird.