ðɛɹ sˈaɪz vˈɛɹiz ɡɹˈeɪtli ænd ðɛɹ sˈoːɹs kæn ɪŋklˈuːd slˈæɡ, dɹˈɔs, flˈʌks ɹˈɛsɪdˌuːz, ænd pˈiːsᵻz ʌvðə mˈoʊld.
Their size varies greatly and their source can include slag, dross, flux residues, and pieces of the mold.