“The Shimmer” is the name given to the mysterious phenomenon that, after a meteor strike, settles along a swampy coastline in Alex Garland’s “Annihilation.” It’s an area enclosed by a fluid, translucent wall bathed in an eerie rainbow glimmer. The Shimmer’s steady expansion threatens to swallow surrounding towns, cities and, eventually, everything. Naturally, this is Florida. Efforts to determine what’s inside the Shimmer have proven futile. Except for one survivor, none to enter have ever returned.