Book about girl who finds eggs of mechanical spiders/scorpions?

Question

I remember starting this book several times in the early 2000's.

Facts I vaguely recall:

• A female main character, probably teenage or preteen.
• She has found/acquired eggs of these robotic/tech/mysterious scorpion-spider-things, and is attempting to raise them separately.
• One of the creatures is aggressive, and I believe kept in a box in a basement/garage. The other is kept in her bedroom closet or under her bed?
• I believe the cover may have portrayed a mechanical spider/scorpion.
• I have a vague sense that it may have used themes common to coming-of-age books written for adolescents.

I never made it far into the book, and remembered finding it particularly stressful as a young reader (somewhere around 7-9).

My mother often grabbed cheap/used sci-fi/fantasy novels wherever she could find them due to my voracious reading, one other book I remember reading around that time was The Game. Real shot in the dark, but this question has been lodged in the back of my head for over a decade now.

Answer 1

I'm pretty sure that you're describing "The Boxes" by William Sleator.

Here's the Cover Blurb:

Annie's Uncle Marco goes on one of his mysterious trips, leaving her in charge of two sealed boxes on one condition: she must not open either one while he is away. But she is tempted...and soon she has unleashed the unspeakable. The creatures inside the box are crab-like and grotesque. And they possess a power Annie could never have imagined: the power to transmute time.