Google 'spadix' and see if anything looks like what you have. The spadix is the actual flower of calla (the wrapped portion that surrounds it is called a spathe and is comparable to petals or the calyx of a typical flower) and a mature one will develop seeds.

Callas are not really lilies at all but are members of the aroid family, like jack-in-the-pulpets. The attached link should help with some pics plus give you instructions on how to grow the seed, should you choose to do so.

Here is a link that might be useful: growing calla lilies