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