What is/was a Druid's Egg anyway?

Druid's Egg
AKA: anguinum; glain y nidir; mân macal.

The Druid's Egg (also “glain,” “serpent's egg,” or “snake stone”) was a talismanic object sacred to the Druids. Tales about it resemble those of the Philosopher's Stone sought by the alchemists. Its myths may also be related to those of the Omphalos, a meteoritic stone that was kept at Delphi and was thought to be the egg of the serpent-monster Python. In legends, the Druid’s Egg is credited with endowing its possessor with the ability to obtain almost all he might desire.

In truth, the Druid’s Egg was an egg-shaped talisman made of stone. This consecrated object served as a tool for meditation and magickal focus, and symbolized the promise of renewal and rebirth. They could be made from any stone, and were generally small enough to fit in the palm of one's hand (about the size of a chicken's egg).

The Druid’s Egg appears to have been an object of interest to the ancients, some of whom describe having actually seen and handled it. Among those who have specially described it is the Roman historian Pliny, who claimed he was shown one of these by a Druid from Gaul and called it an "anguinum."

According to Pliny's Natural History, XXIX.52.:

"There is also another kind of egg, of much renown in the Gallic provinces, but ignored by the Greeks. In the summer, numberless snakes entwine themselves into a ball, held together by a secretion from their bodies and by their spittle. this is called anguinum. The Druids say that hissing serpents throw this up into the air, and that it must be caught in a cloak, and not allowed to touch the ground; and that one must instantly take flight on horse-back, as the serpents will pursue until some stream cuts them out. It may be tested, they say, by seeing if it floats against the current of a river, even though it be set in gold. But as it is the way of magicians to cast a cunning veil about their frauds, they pretend that these eggs can only be taken on a certain day of the moon, as though it rested with mankind to make the moon and the serpents accord as to the moment of the operation. I myself, however, have seen one of these eggs; it was round, and about as large as a smallish apple; the shell was cartalaginous, and pocked like the arms of a polypus."

Many species of snake do form such a ball in the cold months, but the few species of snake native to Britain are not egg-layers. A snake which does lay eggs is the python, not found in Britain, but which was kept in the goddess temples of the Aegean; this may be taken as further evidence of an association between the Druids (or their predecessors) and the Delphic cult which kept the sacred Omphalos stone.

Of all the historic sources who have testified to seeing this legendary egg, none claim to have witnessed its creation.

While the Druid's Egg is not a widespread tool in modern Druidism, it is used by some as a ritual implement for grounding and to protect its owner from manipulative magick or other harmful intents by acting as a magickal “shell,” absorbing and transforming any destructive energy.

Apparently, the Druid's Egg was also believed to create a favorable outcome in courts of law; enough so that the Romans outlawed carrying one into any courtroom, and would put to death anyone caught carrying such an object.

In recent times, there has been some debate as to what Pliny is describing: is it made of glass? is it a type of sea shell? Lately, there have been some glass baubles found in Wales and Scotland that some claim are the "eggs" in question, but whether they actually are or not is unknowable.

In Wales, there is still some belief in the objects; they call them mân macal (snare stones), and glain y nidir (the snake's jewel).

References:
Jones' Celtic Encyclopedia

Pagan Wiki (The Free Pagan Omnipedia)