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