silurian period silurian order psilophytale ordovician period psilophytale
spiny scales on back black-and-white striped chest a row of tentacles or antennae a plant-like structure with gills one or more spines on the underside of the shell
spiny ridges along its back the presence of fossils or other artifacts spines or ridges on the exoskeleton scales and ridges along the back large, ridged scales on the back of the head
a rock on a black background
spiny ridges along its back fossilized the presence of fossils or other artifacts spines or ridges on the exoskeleton scales and ridges along the back
trilobite which has two-lobed tail trilobite which has long antennae trilobite which has segmented body fossil which has the fossil may be of a plant, animal, or bacterial organism fossil which has usually found in sedimentary rock
trilobite which has two-lobed tail trilobite which has long antennae trilobite which has segmented body trilobite which has compound eyes trilobite which has short, jointed legs
trilobite mustelinae fossil ankistrodesmus cretoxyrhina
trilobite fossil chiton fragment layer
muscle which has striated pattern of small lines fingernail which has ridges and grooves in the nail surface comb which has the teeth may be spaced evenly or with varying widths trilobite which has short, jointed legs trilobite which has two-lobed tail
tripe which has small ridges or protrusions along the edges fossil which may appear as an impression, cast, or mold of the original organism trilobite which has segmented body fossil which has the remains of a long-dead organism trilobite which has shell-like exoskeleton