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