No responses to this one - I guess I made it too easy? This is a beautiful example of a Trichuris trichiura or whipworm egg. Note that it is a mature specimen; the egg has embryonated and there is now an easily visible larva inside. It is unusual to see eggs in this advanced state of development since maturation usually occurs in the soli.
To answer the second question: the infective form is the embryonated egg shown here. It is ingested in fecally contaminated food or water, and the larvae hatch in the small intestine. The adults then take up residence in the cecum and large intestine.