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