As magma meets the water, it 'cools and solidifies', adding to the 'edges of sideways-moving plates' as magma piles up along the crack, a 'long chain of mountains' forms on the 'ocean floor', this process or the chain is called Seamount.
<u>EXPLANATION:</u>
When the magma cools or make contact to water than it starts to turn solid and it starts moving up the building blocks while cooling.
Magma is a hot semi-fluid or fluid material which is found within or below the 'earth's crust' from which 'lava' and other 'igneous rock' is formed by process of cooling.
