The rock is made of fine coral fragments and the remains of forams (living sand), and the dark bands are layers of weathered volcanic sediment.
(The rock; is made; of fine coral fragments and the remains of forams (living sand) (the dark bands; are; layers of weathered volcanic sediment)
The rock the dark bands
is made are
of fine coral fragments and the remains of forams (living sand
layers of weathered volcanic sediment