Even today in Somerset, locals use the term "spunky" to refer to Will-o-the-Wisps. A "Will-o-the-Wisp" is a ball of light seen at night rising up from a marsh or bog. The usual physical explaination for this light is "marsh gas" --i.e. methane. Many metaphysical explanations have also been offered to account for "spunkies."

In Somerset there is an explicit belief that Will o' the Wisp is a spunky, the soul of an uncristened child. In the Folklore Society publication County Folklore vol. VIII, Ruth Tongue says:

Will o' the Wisps in Somerset are called 'Spunkies' and are believed to be the souls of unbaptised children, doomed to wander until Judgement Day. These are sometimes supposed to perform the same warning office as the corpse candles.

Stoke Pero Church is one of the places where 'they spunkies do come from all around' to guide this year's ghosts to their funeral service on Hallowe'en. One St John's Eve, an old carter called me to watch from Ley Hill. The marsh lights were moving over by Stoke Pero and Dunkery. 'They'm away to church gate, zo they are. They'm gwaine to watch 'tis certain, they dead cannies be.'

It's not surprising that glowing lanterns carved into eerie faces came to be named after glowing lights thought to be the spirits of dead children. In contrast to American Jack-o-Lanterns which are meant to sit around on porches or windowsills, punkies are meant to be mobile. Mangle-wurzel punkies are suspended from strings like marionettes. Held by black-clad humans in the dark, they appear as glowing faces hovering over the road, just as the Will-o-the-Wisps hover over a bog.