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