Although a diatom is a microscopic plant, it can grow in huge quantities until the resulting mass becomes visible to the naked eye.
(a diatom; is; a microscopic plant) (it; can grow; T:until the resulting mass becomes visible to the naked eye) (the resulting mass; becomes; visible to the naked eye)
a diatom it the resulting mass
is can grow becomes
a microscopic plant
T:until the resulting mass becomes visible to the naked eye
visible to the naked eye