Regarding the Unicorn. Joseph consisted of two tribes, Ephraim and Manasseh. The two symbols of Joseph mentioned in Scripture are the Bull or Young Bull ("BULLOCK") and the Unicorn.
HIS GLORY IS LIKE THE FIRSTLING OF HIS BULLOCK, AND HIS HORNS ARE LIKE THE HORNS OF UNICORNS: WITH THEM HE SHALL PUSH THE PEOPLE TOGETHER TO THE ENDS OF THE EARTH: AND THEY ARE THE TEN THOUSANDS OF EPHRAIM, AND THEY ARE THE THOUSANDS OF MANASSEH": [DEUT 33:17].
Here we have two symbols applied to Ephraim and Manasseh and since each Israelite Tribe had its own symbol we may assume that each of the two symbols belonged to one of the two tribes. In the verse above the word translated as BULLOCK (young bull or bull calf) is "SHOR" which actually means "bull" (but not necessarily "young bull") though elsewhere Ephraim is nicknamed a "young bull":
[Jeremiah 31:18] I HAVE SURELY HEARD EPHRAIM BEMOANING HIMSELF THUS; THOU HAST CHASTISED ME, AND I WAS CHASTISED, AS A BULLOCK UNACCUSTOMED TO THE YOKE: TURN THOU ME, AND I SHALL BE TURNED; FOR THOU ART THE LORD MY GOD.
Here Ephraim is called a "young bull". The word used for "young bull" (i.e. "bullock") in Hebrew is "AEGEL". In Ancient Hebrew the word "Aegel" could also actually have been pronounced as "angle". Historically this very name "Aegel" was a diminutive (favorite nickname) for the ethnic term "Angle". Together with the Saxons, Jutes, Vandals, and others the Angles conquered from the Celts the land that was later named England.
The Angles gave England (i.e. “Angle-land”) its name. The Angles were also called “Aegels”. The appellations “Angle” and “Aegel” were employed interchangeably. The Hebrew word for young bull is "Aegel". Rashi (Rabbi Shlomo Yistchaki 1040-1105 CE) was the foremost Medieval Jewish Commentator. In commentating on this verse (Jeremiah 31;18) Rashi states that the Hebrew word “Aegel” (Young Bull) was a name applied to Ephraim.This accords with the simple meaning of the verse. This was another name applied to the English. The English now nickname themselves "John Bull". This is an important point: the verse is strongly indicating that the English (Angles) are to be identified with Ephraim. We therefore have grounds to ascribe the bull symbol to England which leaves the unicorn sign for Manasseh. In addition it is hinted that the section of Israel represented by the horns of unicorns in the last days would be the most powerful.
[Numbers 24:8] GOD BROUGHT HIM FORTH OUT OF EGYPT; HE HATH AS IT WERE THE STRENGTH OF AN UNICORN: HE SHALL EAT UP THE NATIONS HIS ENEMIES, AND SHALL BREAK THEIR BONES, AND PIERCE THEM THROUGH WITH HIS ARROWS.
The Midrash (Numbers Rabah 2;7) says that the unicorn is the symbol of Manasseh and the bull that of Ephraim. It is true that the unicorn is now part of the symbolic coat of arms of the UK but they derived it from Scotland which has two unicorns on its standard. The USA is dominated by Manasseh. The above verse is hinting that Menasseh (symbolized by the unicorn) would end up being the most powerful tribe.
Getting back to the Midrash:
The Midrash (Numbers Rabah 2;7) says that the unicorn is the symbol of Manasseh and the bull that of Ephraim. The Midrash accords with a logical understanding of Scripture. A Midrash is a Rabbinical explanation from the Talmudic era explaining Biblical verses that was accepted at the time as worth recording for future study. Just because the Midrash says something I do not expect you to. I do not accept all Midrashim. Sometimes they are difficult to understand and at times they may appear to contradict each other. Nevertheless they often contain insights to Biblical passages ands/or recall genuine traditions. The Talmud sources, Midrashim, and related sources often correspond with Brit-Am findings and to my mind this shows that we are on the right track. This especially helps where we have an interpretation of Scripture that other people (including some religious Jews) might not agree with.
Excerpt from Yair Davidiy's "Brit-Am Now" -476