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