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