Representative organism Type of symmetry (Radial, Bilateral, or None) Type of skeleton (ENdoskeleton, EXoskeleton, or None) Type of appendages (Jointed, Not Jointed, or Absent) Segmentation (Present or Absent) Sponges
Cnidarians
Roundworms
Annelids
Mollusks
Arthropods
Echinoderms
Vertebrates

Sponge; Radial Symmetry; Endoskeleton; Absent Appendages; Absent Segmentation

Cnidarians; Radial Symmetry; No Skeleton; Non-Jointed Appendages; Absent Segmentation

Roundworms; Radial Symmetry; No skeleton; Absent Appendages; Absent Segmentation

Annelids; Radial Symmetry; No skeleton; Absent Appendages; Present Segmentation

Mollusks; Bilateral Symmetry; Exoskeleton; Non-Jointed Appendages; Absent Segmentation

Arthropods; Bilateral Symmetry; Exoskeleton; Jointed Appendages; Present Segmentation

Echinoderms; Bilateral Symmetry; Endoskeleton; Non-Jointed Appendages; Absent Segmentation

Vertebrates; Bilateral Symmetry; Endoskeleton; Jointed Appendages; Absent Segmentation

they have identical fossils of organisms that have evolved over time.

both have animal fossils preserved in them due to weathering and erosion.

they contain different fossils because life on earth has changed through time.

the fossils in them were formed on the surface of earth due to exposure to sunlight.