Is it a fat little worm?

 
No, it's a crassula "Ghost cactus" baby which is all of 1 inch long, the mother petal included.

If you want to give fun in the garden to kids, get a Crassula and take one of the petals off (or a donkey tail sedum, they make teeny tiny babies, too.) and lay it next to it's parent plant in the pot. In a few days little red roots come out and start to bury themselves in the soil, and baby plant is born. Cool, Yes?