Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
crusto, āvi, ātum, 1, v. a. [crusta], to cover with a rind, shell, incrustation, plaster-work, embossed figures, etc. (post-Aug.): mala gypso, Plin. 15, 17, 18, § 64: domum marmoribus, to incrust, Luc. 10, 114; cf. Isid. Orig. 19, 3: portam crasso ferro, Amm. 24, 2, 14: vasa potoria crustata, Paul. ex Fest. p. 53, 6 Müll.: crustata crassities pectoris et ventris, incased with fat, App. M. 7, p. 189, 18.
Subst.: crustāta, ōrum, n. (sc. animalia), crustaceous animals, shellfish, Plin. 11, 37, 62, § 165.