Black pudding

A black pudding was an ooze resembling a bubbling, heaping pile of thick black goo.

Description
The average black pudding measured 15 ft (4.6 m) across and 2 ft (0.6 m) thick and they weighed around 18,000 lb (8.2 mt). While most of these monsters were an inky black, some could be brown, grey, and even white.

Behavior
These creatures were mindless underground-dwelling scavengers that wandered and absorbed whatever they found.

Combat
Black pudding attacked by grabbing, grappling and constricting prey directly into their liquid-esque mass. Like other oozes they also secreted a deadly acidic substance which strongly and quickly dissolved weapons, clothing and organic tissue alike. When slashed at or pierced, the black pudding split into two smaller puddings, both of which would do the same; this continued until they were too small and weak to do so further.