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