Are those the shrimp I gave you? They are looking fantastic! Don't worry if a single shrimp dies. It can be from a bad molt, age or other normal issues. If you see more than one at a time, that is when you should begin to investigate. Soon enough they'll breed up a storm. Overfeeding is the main reason shrimp died for me outside of that.
Without Algae, death of mankind would be inevitable.