Wriggleghasts have long fascinated and terrified those who work the soil, and for good reason. Their pudgy, pink forms vaguely resemble some sort of deformed human shape, and so the stories rose. They were worms that fed on human flesh and gained a part of their soul. They were the souls of unborn babies, wriggling forever in the earth and craving human form. They were benevolent earth spirits, worthy of being placed back with care so that they might protect the crops.
In reality, these infant-sized creatures are none of those things. They are merely worms, and particularly grim-looking worms at that. It is uncertain what they primarily use their arms for, but they carry surprising strength for their size, capable of pulling about their body when they emerge onto the surface, rare as that is.
In the far north, they are even rarer to see on the surface, as moving underground is much slower work. They produce prodigious body heat that they use to thaw the permafrost before them. They are purely vegetarian, feeding mostly on roots, and in their taiga subspecies, pine needles, of which they are the primary decomposers.
Almost nothing hunts them, for the simple reason that they are beneath notice. It is far too much work to dig through the permafrost for them. Their most frequent predator is the male timber mantis, especially young ones too small to yet take down a yeti or a wooly yale. They have no defenses besides their choice of home, which does no good against a superpredator that shoves through rock-hard dirt with sheer might. But for their softness and weakness, nothing in the north would run without them. They are the ultimate decomposers of plant matter, keeping the swamps clear.