Shimmer

Throwing an item into Shimmer will either:

In the first two cases, the item will splash into the Shimmer and slowly rise upwards about 1.5 blocks above the Shimmer, where it can be picked back up.
Item quantities are respected during the transformation.
Shimmer-produced items have noGravity.

A successful Transmutation awards nearby players with Shimmer In The Hole, as well as XPlosion if the item transmutes into XP.
A successful Uncraft awards nearby players with Minetfarc.

A Projectile that touches Shimmer bounces back in the opposite direction with a small speed boost. It can't bounce again for 5 ticks after bouncing.
The projectile breaks into sparkles on its 6th bounce.

Any non-Player mob that touches Shimmer gets Invisibility for 30 seconds without particles. The mob won't be able to get Invisibility again for 40 seconds after the initial contact.

Players that touch Shimmer are awarded Ghostly Dive, and are inflicted with the Shimmering effect.

Shimmering temporarily turns players into Spectator Mode. After 1 second (by default) they turn back into their original game mode.
The duration of Shimmering is dictated by the shimmeringDuration gamerule. If it's 0, it disables Shimmering all-together.

Once the Shimmering effects ends, the player can stay in Spectator mode longer if they happen to be inside Shimmer - up to 2.15 seconds longer (by default - dictated by the shimmeringBonusDuration gamerule). If using this extra duration, the effect will end immediately upon exiting the Shimmer.

Players that are wearing Chromatic armor or that are in Creative mode are immune to Shimmering.

Players becomes immune to the effects of touching shimmer if they're wearing at least one piece of Chromatic armor.
To obtain this enchantment, one must throw a piece of armor into Shimmer and it will come out Chromatic. This is the only way to obtain the enchantment in Survival mode.

Chromatic can be removed by throwing it in Shimmer again, but be warned!- Using a Grindstone to remove Chromatic works, but shimmering it again after that will do nothing - locking it out of Chromatic forever. (oh no!!!!!)

Shimmer can be found exclusively in Aether structures underground, where you'll find a decent supply of it.

Notably, Shimmer cannot be picked up in a Bucket. It also doesn't produce infinite sources, so the only way to collect and move Shimmer is with a Shimmer Shell.
This means that to move Shimmer, you need access to Shulker Shells.

A Shimmer Jar can also be used to store liquid Shimmer, but it also requires a Shimmer Shell to be crafted.

Some other blocks are also able to items, but only items.

It's from everyone's second favorite survival sandbox game. Terraria.'
Many of the Shimmer-exclusive items also are.

Just Uncrafted a bunch of Trapped Chests.

Poppies float saddeningly in the Shimmer (They don't have a Transmutation)

Admiring various Shimmer-related items.

Transmutating Smooth Netherrack into Blue Smooth Netherrack using various blocks.

Jumping into Shimmer.

Bouncing various projectiles inside a Shimmer Bouncy Castle.