Feet
Spine
Mouth
Nose
Subtidal area only
Both intertidal area and subtidal areas
Intertidal area only
On the beach
Strongylocentrotus
Animalia
Echinoderms
Purpuratus
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
Sea cucumbers
Other sea urchins
Small fish
Algae
Toothpick
Dome
Pentamerous
Porcupine