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