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