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