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