Obsidian Watcher

Mob

The Obsidian Watcher is a floating eyeball mob that cries purple tears that inflict the weakness effect. It sticks around one location and can spawn as a partner for the sculk watcher in the stronghold. It only cries while targeting a mob. The weakness effect makes it harder to kill entities. In particular, silverfish only trigger other infested blocks when they are hit if they survive the hit. The weakness will help them survive the hit resulting in triggering infested blocks.

Redstone

When a watcher dies its eye falls and can be preserved through means such as bubble column stasis chambers. The preserved eye will continuously cry inflicting its associated potion effect.

Eye of ender

Can be spawned when a watcher spawns from an Eye of Ender while in a block of crying obsidian. See Eye of Ender.