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