rusticlen.
/ˈrʌstᵻkl/, U.S. /ˈrəstək(ə)l/ An elongated structure often found on underwater shipwrecks, somewhat like a stalactite or icicle in appearance, consisting of microbial and fungal growths inside a layer of iron oxide.
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1986 Science 9 Aug. 86/1 The hull and other steel objects were heavily rusted..by what Ballard calls ‘rusticles’.
1987 R. D. Ballard Discovery of Titanic viii. 116 Near the upper railing..reddish-brown stalactites of rust hung down as much as several feet, looking like long needle-like icicles. This phenomenon, the result of iron-eating bacteria, was well known... I subsequently dubbed them ‘rusticles’, a name which seems to have stuck.
1991 Proc. U.S. Naval Inst. June 56/2 A few rusticles have formed on the armor surfaces.
2004 J. Woodward Midnight Zone 33/2 You use the submersible's mechanical hand to snap off some rusticles and put them in the sample basket.
2007 T. Friend Third Domain v. 156 Anatoly used the manipulator arm to touch a portion of a rusticle that had taken over a hulk of steel torn from the ship.
This is a new entry (OED Third Edition, March 2011; most recently modified version published online March 2022).
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n.1986