spon·gin 
(spŭnjĭn)
(spŭnjĭn)n.
A sulfur-containing protein similar to collagen that forms the elastic fibrous structure of certain sponges.
- poppy seed
- Popsicle
- pop tent
- pop the question
- pop-top
- populace
- popular
- popular front
- popularity
- popularization
- popularize
- popularizer
- popularly
- populate
- population
- population explosion
- population genetics
- population inversion
- populism
- populist
- Populist Party
- populous
- populously
- populousness
- Populuxe