riddle - I am the first in Earth, What am I?

I am the first in Earth,
The second in Heaven.

I appear twice in a week,
Never in a month,
Once in a year.

And I am found in the middle of the sea.

What am I?

Answer

What am I?

The letter "E"

I am the first on Earth,

E-arth

The second in Heaven.

h-E-aven

I appear twice in a week,

w-EE-k

Never in a month,

month <--- no E!

Once in a year,

y-E-ar

And I am found in the middle of the sea.

s-E-a