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