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