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