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