Glashtyn

Glashtyn (Manx: glashtin, glashan, glaistyn, glastyn; pronounced /ˈɡlæʃtᵻn/) is a legendary creature from Manx folklore. The word glashtin is thought to derive from Celtic Old Irish: glais, glaise, glas, meaning "stream", or sometimes even the sea.

By some accounts, the glashtin is a goblin that appears out of its aquatic habitat, to come in contact with the island folk; others equate it to the water horse known locally as "cabyll-ushtey".

Shapeshifter theory

The two conflicting accounts above can be reconciled by the trick of regarding the Manx glashtin as a shape-shifter. Recent literature embracing this notion claims that the equine glashtin assumes human form at times, but betrays his identity when he fails to conceal his ears, which are pointed like a horse's. One modern tale relates how a fisherman's daughter outwitted the glashtyn whom she recognized by his horse's ears, resisting his temptation of a strand of pearls dangled in front of her, and holding out till the red cockerel crowed to announce (prematurely) the break of dawn (Matthews & Matthews 2006,). Here it is said that the glashtyn can transform whenever upon a dunghill.