"layers" - key terms from Wikipedia

absorbent layers
abstraction layers
all three layers
annual layers
ash layers
background layers
boundary layers
cell layers
deep layers
deeper layers
deeper skin layers
dough layers
emulsion layers
ferromagnetic layers
first two layers
four layers
germ layers
graphene layers
having active and passive layers
ionospheric layers
layers
layers in each superconducting block
layers of netting
layers of peptidoglycan
layers of the pleura
layers of the skin
layers together
mac layers
main cell layers
metal layers
mineralized layers
more layers
outer layers
outer layers of the grain
outer layers of the star
resistant layers
rock layers
six layers
skin layers
snow layers
soil layers
superficial layers
these two layers
transport layers
two layers
up to two layers
upper layers
widget layers