opus vermiculatum---taken from the latin word 'worm.' It refers to lines of tesserae that snake around a feature in the mosaic. Often 2-3 rows of opus vermiculatum appear like a halo around something in a mosaic picture, helping it stand out from the background.
EUROPA ON THE BULL / ROM. MOSAIC / C1 AD. Mythology / Europa. Roman, 1st half of 1st century AD. Mosaic after a painting by Antiphilos (?) – “Europa on the Bull”. (Zeus in the form of a bull abducts Europa, her father Agenor above). Opus vermiculatum, 85 × 84.5cm. Found: Praeneste.
200-100 BCE Alexandria Egypt. Floor Mosaic Roundel: A Dog & An Overturned Gold Vessel. The quality is fantastic, and this period represents a high point in the mosaic craft in the Greco-Roman world. Many of the tesserae are only 1-2mm across, which allows the mosaicist to achieve a painterly effect. The technique is called "opus vermiculatum", or ‘wormy work’. The Greco-Roman Museum in Alexandria. I can't help but wonder if this wasn't the inspiration for RCA Victor's "His Master's Voice".
Central panel (emblema) from a triclinium mosaic showing marine life, the panel shows eleven different edible sea-creatures, all identifiable today, made using tiny tesserae in a technique called opus vermiculatum - (I cent.AD) from Populonia, Tuscany, Italy - British Museum