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