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