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