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