Could Somebody Tell Me

I'm wondering if anyone here can identify which Godzilla movie this is. I forgot its name and it is my favorite (I know, pretty sad). I'm thinking its Godzilla vs Biolanette, but the description doesn't quite fit it. Here is what I can remember: Some sort of gray space blob, looking like an asteroid comes down to earth. After a tiny bit, it starts flying around. Jump forwards near the end of the movie, Godzilla and the blob (who had transformed into some kind if monster) are fighting. The thing I remember most is when the monster opens its mouth and starts eating Godzilla head first. The monster starts to grow the same kind of spikes on its back that Godzilla has. But then, Godzilla's plates (excuse me, I'm referring to Stegosaurus) starts to turn red, and then Godzilla destroys the monster with his fire breath from practically inside. The description is probable not spot on accurate, since I haven't watched any Godzilla films in like five years. If anyone could tell me what it is, I would really appreciate it.