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