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