Sand is porous, so air get get through it, but mud can keep air out.
Nothing
No, because mud is a mixture of water and dirt, which is denser than water, so the average density is greater than water. However, water tends to mix with mud, which may give the illusion that it is more dense.
mud+sand=clay
Yes lol
An octopus can hide its body in the sand or mud.
Shale/ Limestone
Shale
The result is called a lahar, a heavy, viscous mudslide that can create even more damage than a simple flood of water. Originally containing water condensed from lava, and meltwater from any existing glaciers on a volcano, a lahar can flow through existing lakes and rivers, scouring their shores and channels and carrying debris from the trees, buildings, and bridges destroyed in its path.
An octopus can hide its body in the sand or mud.
An octopus can hide its body in the sand or mud.
An octopus can hide its body in the sand or mud.