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