This animate pile of mud seems barely able to maintain the semblance of a humanoid form made of dripping sludge.
Speed 20 ft., burrow 10 ft., swim 30 ft.; earth glide
Str 20, Dex 12, Con 17, Int 4, Wis 11, Cha 11
A burrowing mud elemental can pass through dirt, gravel, or other loose or porous solid matter as easily as a fish swims through water. It cannot use this ability to pass through a solid barrier such as a stone or brick wall. Its burrowing leaves behind no tunnel or hole, nor does it create any ripple or other sign of its presence. A move earth spell cast on an area containing a burrowing mud elemental flings the elemental back 30 feet, stunning the creature for 1 round unless it succeeds on a DC 15 Fortitude save.
The mud from an elemental’s entrap ability can be washed away in 1d3 rounds of immersion in water.