Anything you like. We have settled for 10 characters (0,1,2,...,9) for the decimal system but different cultures use different shapes for these numbers. There are, of course, the Roman numrals for all but 0.
Then there are letters of the alphabet that are used in the hexadecimal system (A-F), Greek and Roman letters in algebra, etc.
There are an unlimited number of things that a squirrel can symbolize. Squirrels can symbolize love or chaos in the world.
Bells typically are used to symbolize weddings. Bells may also be used to symbolize music, death, peace, or gathering for example.
it is a good example of a prime number
There are a number of things a sea horse could symbolize. A sea horse could symbolize peace or fragility for example.
There are an unlimited number of things that a butterfly tattoo on the left shoulder could symbolize. It could symbolize peace for example.
The color green is often used to symbolize growth, renewal, and harmony in literature or poetry, but it is typically not used to symbolize danger or caution.
Nuestra Familia.
The number of states.
The number seven is [perfection to God]
A square number because 18*18 = 324
It might symbolize light or illumination. It depends on what context it is being used.
The Greek letter "B" (beta) is commonly used to symbolize the magnetic field in physics.