Curse Jar

General

Tall earthenware vessels which emit dark smoke when the player is nearby. Sounds like giggling monkeys.

Location

Shaded Woods
Found throughout the map.

Huntsman's Copse
Found throughout the map near the Undead Lockaway bonfire.

Shrine of Amana
Found throughout the map.

Strategies

Smash them, either by rolling over them, shooting them with heavy enough arrows, aiming spells at them or with consumables like Firebombs.

Summoned Phantoms cannot be cursed, so they can destroy them with no risk

The dark smoke released by vases causes the Curse status effect, though simply moving close enough to the jars will get your curse meter to rise.
The jars' effect can travel through walls and floors. However, unlike poison or acid jars, rolling over the jars doesn't coat you in anything, instead ending their curse-inducing effect.