We all thought he had gone what is the tense scentence

If you say, "Had gone," that is the past perfect tense. How are those two tenses different? While the normal past tense says that the action happened at that time in the past, the past perfect tense says that the action happened before that time in the past.

the black night was split open like the coconut

it says that it was totally black in the mind of a person but suddenly his mind opened like a coconut with the sweetness of the coconut water and the white color inside it.

or

the black night was thrown like a coconut and it slit apart with its sweet water coming out .

onto a large boat, and mark the water level that the boat sinks to. then, take the elephant out and put a bunch of marked weights onto the boat until it reaches the same water level. add up the masses of the weights to get the weight of the elephant.