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