Urgent Really need help please!!

Well glad that mystery is solved, lol. Sponges are good right? They can't hurt anything right? lol. I really thank you for your help and putting up with all my silly pictures and questions. I defiantly want what's best for this tank. I would hate for it to go belly up because some stupid "bad guy" took it over lol.

THANK YOU! THANK YOU! I will do some research on these sponges and hopefully, maybe one day I'll actually understand. P.S. When I was looking up sponges during post, i found some really cool looking ones lol.