This is a likeness of the chalice used by Herne the Hunter whilst in communion with his Sons, Robin Hood.
A single bull-headed bronze goblet was used sporadically through the three years of production. In the series opener ,it is present in his cave and by drinking the potion from it allows Robin to see visions of things yet to come. It then is seen later in the first series, but is being used by Robin to pass around a blessing drink (wassail) which all the merry men partake in, including the Chevalier DeGuise, aka King Richard 'Lionheart.' It is used once by Herne's other Son, again to provide insight.
The exact screen-used chalice has yet to be found, but this is an almostly exact version of the distince animal headed vessel, except it has more of a linear 'floral' patternation, whereas the production version depicts seated figures from Minoan mythology. I highly suspect one to be Dionysus.
They are antique copies of real Bronze Age Greek vessels, made in Bronze. Most in antiquity tended to be porcelain, except for higher end ones which were, indeed, made of bronze, and intended to pour libations during feasts and to honour the gods.
