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