For one thing it is insulated from outside weather and sunlight which could cause evaporation and erosion. it"s underground, certain factors are either ruled out or minimized, subways are weather proof, in most instances.
It grows to be about 4 to 5 feet
The longest crystal ever recorded is a selenite crystal found in the Cave of the Crystals in Chihuahua, Mexico. This crystal measures about 12 meters (39 feet) in length and is estimated to be around 500,000 years old. These massive selenite crystals were formed in a unique geological environment, resulting in their extraordinary size.
They grow to 20 feet - 30 feet.
1848 feet long x 456 feet wide x 135 feet high
A small quartz crystal can grow about 1mm a week assuming it is in a stable matrix.
A African Black Mamba Can Grow To Be 14 Feet Long.
it can grow up to 12 feet it can grow up to 12 feet
1 foot long viper 1
It take at least 4 hours to grow
a falcone grow to 2 or 3 feet long
It is 17,500 Feet Long Peoples
a jellyfishes tetacles can grow to be over 150 feet long not counting the "bell" or "hood".