HMS Unicorn, built in 1824, is one of the oldest continuously afloat ships in the world. Built to replace ships lost in the Napoleonic Wars at the end of the age of sail, her service history involved no major battles, and hence the historic fabric of her hull is largely intact. Samples were collected directly from the wet bilges with the aid of a hammer and chisel. The hold has previously been treated for fungal activity , although the agent used is unknown.