It is hard to see the hexagram that frames this zodiac floor, because the camera is too close to the mosaics, but you can see it better here.
In the middle of the picture there are seven Roman emperors who represent the seven days of the week or the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. Around them the animals sacred to them: wolf, eagle, dove, horse, bull and goat. Around them the signs of the Zodiac.
This well preserved zodiac floor from the third century C.E.is now in the Bardo Museum in Tunis, but it was discovered in Bir-Chana near Zaghouan ,in central Tunisia.
Picture is courtesy of "bibbijian" who published it on Flickr.