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