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