Subtidal area only
Intertidal area only
Both intertidal area and subtidal areas
On the beach
Porcupine
Dome
Toothpick
Pentamerous
Purpuratus
Animalia
Strongylocentrotus
Echinoderms
Because sea urchins have large numbers of eggs
Because the eggs make great omlettes
Because a sea urchin's egg is relatively big
Because sea urchins have large numbers of relatively big eggs
Mouth
Feet
Spine
Nose
Other sea urchins
Small fish
Algae
Sea cucumbers