On the front of the altar is the Lamb and seven seals, from the Book for Revelation (Revelation 6).  On one side of the altar is a crown of thorns and the nails from this crucifixion.  On the other side is grapes which represent the fruit of the vine that becomes our spiritual drink (The Precious Blood) at Mass.  On the back of the altar is a symbol of an anchor representing the theological virtue of hope.  Hope is know as the Anchor of the Soul in Hebrews 6:19.   It also has an 'X' representing the Greek letter Chi, which is the first letter in the title Christ in Greek (Χ Ρ Ι Σ Τ Ο Σ = Ch R I S T OS, which means anointed. It is also the Greek translation of the Hebrew word Messiah)

Loaves and Fishes on the Lectern and the Tabernacle.   Fishes are also located on the Baptismal Font.