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