Laudator Temporis Acti

Figure of a crouching African boy (Boston, Museum of Fine Arts, accession number 01.8210): I can't find any extended discussion of this statuette, but maybe I'm looking in the wrong places, or I don't have access to the right books. It appears as figure 42 in Frank M. Snowden Jr., Blacks in Antiquity: Ethiopians in the Greco-Roman Experience (1970; rpt. Cambridge: The Belknap Press of Harvard University Press, 1971).

The anklets are usually understood to be constraints, not decorations. On leg irons see Frederic D. Allen, "On 'Os Columnatum' (Plaut. M.G. 211) and Ancient Instruments of Confinement," Harvard Studies in Classical Philology 7 (1896) 37-64 (at 41, references are to plays of Plautus, unless otherwise indicated):

Catenae is a general term, but it ordinarily implies some sort of shackles, to which the chains can be attached. Among the catenae singulariae (Capt. 112) with which Hegio's two prisoners are bound and which allow them some liberty of motion (sinito ambulare, v. 114) is a collare (v. 357), and in Menaech. 84 f. compedes are included in the term catenae. Compedes are very often mentioned. They are shackles for the leg (crura, Capt. 652; suram, Pseud. 1176) of iron (ferreas, Pers. 573), put on by a smith (Capt. 733, 1027) and worn constantly (Cist. 244), so that they shine through friction (rediget in splendorem compedes, Aul. 602). It is possible to move about and work in them (Capt. 723 f., 736, 944), but their weight (ten pounds, Liv. XXXII, 26; fifteen pounds, XII Tables) effectually prevents escape. They consist (Menaech. 85 f.) of a ring (anus) fastened with a rivet (clauos), and putting them on is called impingere (Capt. 733, Pers. 269, 573). They clank as one walks (tintinnabant compedes, Naevius v. 114 R. = Fest. p. 364 M.), which shows that they are connected by a chain. Those who wear them are tintinnaculi viri (Truc. 782).