וְעָשִׂ֣יתָ קַרְנֹתָ֗יו עַ֚ל אַרְבַּ֣ע פִּנֹּתָ֔יו מִמֶּ֖נּוּ תִּהְיֶ֣יןָ קַרְנֹתָ֑יו וְצִפִּיתָ֥ אֹת֖וֹ נְחֹֽשֶׁת׃
And thou shalt make the horns of it upon the four corners thereof; the horns thereof shall be of one piece with it; and thou shalt overlay it with brass.
Read kabbalistic (mystical) interpretation of Exodus 27:2: and classical mystical sources.