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