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