Gurglings

Gurglings are a pair of bosses that can appear in Error: The given stage ("The Basement") does not exist..

Behavior (Boss)

The Gurglings spawn as a pair and have two attacks in total.

The Gurglings will rush towards the player when aligned with them in any cardinal direction, leaving behind Red Creep until it has run into a wall.
After rushing, the Gurglings will pause for a brief moment, and then spawn 0-2 Attack Flies.

Black: Gurglings will spawn Troll Bombs at regular intervals instead of red creep when rushing towards Isaac. They take only 5 damage from their own bombs.
Yellow: Three Gurglings will appear instead of two. They are faster and do not leave any creep.

Gurglings can spawn in normal or tiny rooms.

When fighting Gurglings, the following obstacles can spawn:

Nothing
2 rocks (1 in top-right and 1 in bottom-left corners)
2 urns (1 near top-left and 1 near bottom-right corners)
7 red poops & 6 pits in the bottom of the room
4 red poops (2 in top-right and 2 in bottom-left corners, covered with 3 rocks and 1 metal block each)

In tiny rooms, one Gurgling will appear behind pits.

Gurglings are ordinary enemies on later floors and behave slightly differently from their boss counterparts.

Gurglings appear to be the "egg" stage of the Gurdy boss series; Gurdy Jr. being the larva, Gurdy being the pupa, and Mama Gurdy being the adult.
The Gurglings and their poop-themed variant (Turdlings) spawn in groups of three during the Boss Rush.
If the gurglings audio is slowed down or it gets the gigantic version of itself, the audio reveals that it is a little kid saying "Rawr!"
Unlike regular Gurglings, boss Gurglings have a one-second death animation.

Bug!	If you walk into a wall or "wallhack", the Gurglings will not charge effectively invalidating them.

Bug!	If both Gurglings rush towards you at once, only one of the Gurgling's grunting noise file will play.

Bug!	When fought in the Boss Challenge Room, they will appear in their enemy form rather than their boss form, making them much weaker and lacking a health bar.

Bug!	When the Gurglings are slowed and attempt to charge Isaac, they can't move and constantly spawn Attack Flies. Similarly, the "mini-boss" Gurglings attempting the same attack will constantly shoot 6 blood tears.