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