Butterflies go through life cycles containing forms and stages of metamorphosis. The stages, in order, are:

1. Larva
2. Pupa
3. Cocoon or chrysalis
4. Adult

Cocoon/Chrysalis Stage:

Monarch butterflies are one of the most famous butterflies around. Everyone knows them for their brilliant orange and black colors and their beautiful chrysalis. A chrysalis is just the specialized cocoon of some butterflies. While some butterflies use white, stringy, cottony cocoons, some use hardened shells, which are called the chrysalis.

The monarch butterfly pupa creates the chrysalis shell around it. It normally takes the monarch pupa 5-10 days to finish the metamorphosis into an adult butterfly. During the metamorphosis, the chrysalis first appears to be a green color (which is/was the same color as the pupa), but as the change progresses, the shell turns black, and then clear. When the chrysalis is clear, you can see the colors and patterns of the new adult butterfly's wings.

Pictures of the Chrysalis:

http://www.ivyhall.district96.k12.il.us/4th/kkhp/1insects/bugpix/Monchrgr.jpg
http://www.emmajesty.com/htmldocs/pagehtmls/monarch/pupa.jpg
http://www.emmajesty.com/htmldocs/pagehtmls/monarch/darkpupa.jpg
http://www.emmajesty.com/htmldocs/pagehtmls/monarch/sidereadypup.jpg
http://www.emmajesty.com/htmldocs/pagehtmls/monarch/backpupaready.jpg

More Info:

http://www.zoomwhales.com/subjects/butterfly/species/Monarch.shtml