Why we worship Linga or Siva Linga?

With the blessings of Gurunadhar Thirumoolar and the Almighty Siva

All the content here are given as a gift for me which should be shared.

Siva Temple in India , particularly very Ancient Temples. You will notice the following ( I would have missed many or I may be wrong , please correct me in comments)

1. Four Large Towers which faces four sides ( North South East West)

2. The towers may have stages 1,3,5,7,9,11,13,etc... in odd number 

3. According to the stages of the tower there will be Kalasam (kumbam on top) for example, if the tower stage is 3 then there will be 3 kalasam

4. The temple area will be very huge

Now compare the size of the temple area vs the Siva Linga inside the temple ( 1000000000 : 1 )

Which means the size of the linga is very small compared to the Temple as a whole.

Our Gurunathar Thirumoolar Says in the Book Thirumandhiram 

தெள்ளத் தெளிந்தார்க்கு சீவன் சிவ லிங்கம் 

This means the person whose mind is crystal clear will know that the Jiva (Soul) inside this body is Siva lingam.  

Now start noticing the fingers closely in the hand and notice the shape 

All fingers will be in Linga shape, even our nails will be in Linga shape, our teeth will be in linga shape, our knees, shoulders, toes, our heads , nipples, reproductive organs etc....

Why this body is having this shape rather than some other shape of the animals ?

We cannot create what we don't know. That's what thirumoolar found that the Jiva (Soul) is in Linga shape that's why the body is in Linga shape. This was told in the Thirumandhiram book written by Gurunadhar Thirumoolar.

மானுடர் யாக்கை வடிவு சிவ லிங்கம் - The human body shape is siva lingam.

Now coming to the size of the Jiva  ( Thanks to Thaevaaram.org )

மேவிய சீவன் வடிவது சொல்லிடில்               
கோவின் மயிர்ஒன்று நூறுடன் கூறிட்டு
மேவிய கூறது ஆயிர மாயினால்
ஆவியின் கூறது நூறா யிரத்தொன்றே

To speak of the size of Jiva
It is like this;
Split a cow`s hair soft
Into a hundred tiny parts;
And each part into a thousand parts divide;
The size of Jiva is that one of part
Of the one hundred thousand.

So the size of the Jiva is very small like the 1 lakh times smaller than the size of the cow's hair (width). So this smallest Jiva is running this big body. Again this Jiva is run by Siva. 

சீவன் எனச்சிவன் என்னவெவ் வேறில்லை
சீவ னார்சிவ னாரை யறிகிலர்
சீவ னார்சிவ னாரை அறிந்தபின்
சீவ னார்சிவ னாயிட் டிருப்பரே .

Jiva and Siva
Separate are not;
Jiva knows not Siva;
When Jiva knows Siva;
Jiva becomes Siva.

Jiva is Siva , but Jiva don't know Siva, if Jiva knows Siva. Then this Jiva will become Siva. 

So to know the almighty we should know the Jiva, and get help from Siva to show Jiva to Siva. 

This is why we are worshiping Siva Linga.

I don't know whether I have made my points clear here. Hope this may help some one.

Thanks to Gurunathar Thirumoolar and Almighty Siva.