Front Tagline: They're no yolk!
Back Tagline: Which Came First, the Monster or the Egg? (which makes no sense but let's be with them on the pun)

Official Book Description:
An egg hunt. That's what Dana Johnson's bratty little sister, Brandy, wants to have at her birthday party. And whatever Brandy wants, Brandy gets.
Dana's not big on egg hunts. But that was before he found The Egg. It's not like a normal egg. It's about the size of a softball. It's covered with ugly blue and purple veins.
And it's starting to hatch...

Brief Synopsis:
This kid finds an egg in his backyard. It hatches into a creature that resembles scrambled eggs. He goes to take the creature to a scientist to help identify the creature and the scientist informs him that it is a creature from Mars. The scientist has collected most of the alien egg creatures but appeciates the boy finding another. He has kept them in a freezer in his lab and when the boy decides to leave the scientist informs him that he can't leave, he might have caught a virus or mutation from the creatures. The scientist locks the boy in the freezer with the creatures. The boy thinks he's going to freeze to death until the creatures form a blanket to keep him warm. In the morning, the scientist sees this and tries to kill the boy. The egg creatures form a solid wall and smother the scientist. The boy escapes and gets his parents to drive back to the lab but the egg monsters and the scientist have disappeared. The boy seems to be doing well and feels fine.

But the Twist is
Fine until he stops and squats in the lawn and lays an egg.

the Platonic Boy-Girl Relationship:
Dana Johnson, the male narrator who's honestly a bit of a dick, and his best friend Anne Gravel, who's described as tall and funny, and also disappears half way thru the book.

Questionable Parenting:
When Dana goes missing, his father goes to look for him at the conveniently located science laboratory but somehow doesn't find the time call the police, not even by the time his son wanders back home the next day.

Memorable Cliffhanger Chapter Ending:
Ch 20-21:
"Ive got to find a way out of here," I said outloud, "I've got to!"
And then, I had an idea.
---
Sad to say, it was a bad idea.
The kind of idea you get when you're freezing to death in a total panic.
What was the idea? To call home and tell Mom and Dad to come get me.

Great Prose Alert:
About 40 pages in, the scientist, within two minutes of meeting the child narrator, with almost no provocation, tells Dana "There was a big storm on Mars. Two years ago. It set off something like a meteor shower. The storm sent these eggs hurtling through space."

Conclusions:
I never read this one when I was younger since I'd already abandoned the series, but if I hadn't already quit reading these books at this point, this likely would have done it.