Dip

Dips are small piles of poop, commonly found on most floors. They can also be spawned by some bosses, like Dingle and Mega Fatty, as well as enemies like Squirts upon death and Dingas. They move around by small dashes in random directions.

Corn
Like Dips, Corns dash in random directions. Their dashes are faster and longer, but they have less health.

Brownie Corn
A Brownie Corn is an alternate version of the Corn mainly spawned by the Turdlings, Dangle and Brownie, though they can also rarely be found in some rooms. Despite the different appearances, they behave exactly like normal Corns.

Big Corn
A Big Corn is an alternate version of the Dip with twice as much HP that can also travel over flooded pits. Rather than be mostly harmless, this variant shoots out a piece of corn that heads towards Isaac upon death.

Drip
A Drip is an alternate version of the Dip that rolls around in diagonal directions and can travel over flooded pits. They are also spawned by Splurts upon death and by Clog during battle.

Trivia

 * The Corn has the lowest health of any enemy in the game, tied with the Fly and Drip.
 * Dips are likely a reference to Gels, enemies from The Legend of Zelda: A Link to the Past, as they have nearly the same movement patterns.
 * The name of the Dips is a pun on the term "dipshit", due to their names (Dips) and the fact that they are living fecal matter.