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