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