Hm.. so you believe the scientific concepts but you are not able to understand how can Mahadev exist in his form...
Then take even Mahadeva's form symbolically:
Mahadeva is generally seen wearing a tiger skin, with ash smeared on his body, and the Ganga on his head, and poison in his throat, Snake around his neck with a Trishul, right?
Now when we die, what is left? Ash. Bhasma. This is the bhasma on Lord Shiva. Symbolises we all will become that only one day.
The snake coils around his neck. Usually Snake represents Time (like Adisesha of Vishnu). This time coils around the neck of SHiva, showing that he himself is Time and knows everything.
Tiger is an example of all the evil things around us. BY wearing its skin, he shows that he conquers all the evil.
Poison represents the evil INSIDE us. He stops it from spreading all over, by keeping it in his neck. Thus he prevents evil thoughts also.
Ganga represents purity. Purity is from him. He is everything pure, taht is shown by Ganga.
The moon represents good thoughts. By keeping moon on his head, he shows that he has all supreme thoughts.
Trishul represents three Gunas: Sattva Rajas Tamas. By controlling them, he shows that he is beyond all three gunas. I hope now you understand why this form of God, and that this is not some imagined fairytale of the Rishis.