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