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