This is a mosaic depicting the labeled figures of Andromeda, Perseus, and Ketos, a sea-serpent from which we derive the term “cetacean” for whales. (“Ballene comes from the Latin ballaena, which was borrowed from the Greek phallaina, from phallus, because whales kinda just look like swollen dicks.) The Greek is easy to decipher if you’re familiar with Δ signifying “d, delta” Ρ signifying “r, rho” and Π signifying “p, pi” and if you weren’t now you are. Another thing to note is that the sigmas are what we call “lunate,” meaning that they look like C instead of Σ, but both signify “s.” Here’s the same labeled scene on an older, Corinthian vase:

What in the hell? First off, dude’s written backwards. Early forms of writing both Semitic and European (who got theirs from a Semitic source) could be written backwards and forwards and up and down. There are Greek inscriptions written in the boustrophedon manner, in which the text would go left to right and then right to left. As folks outside of a small scribal class became literate, orientation and direction were standardized, which occurred after eastern and western scripts had already diverged, hence Indo-European left-right and Semitic right-left. This is an early Greek inscription, when writing Greek backwards was as normal as forward, so we get a backward Perseus and Andromeda and a forward Ketos. Greek would later be incapable of this, but it’s possible that the artist intended to have the Ketos forward to show aggression and Perseus and Andromeda backward to show companionship and defense. A couple other peculiar things: the Corinthian alphabet closed their Es, making something like a B (their B looked like an all-right-angled N); instead of inheriting the sigma, Σ, from the Phoenicians, they took the san, M (but with a shallower V between the two upright strokes, basically the same letter angled 90 degrees). It’s a shame we can’t see the M in “Andromeda” because the Corinthians wrote it M, that is, with a deeper angle between the upright strokes than their san, or like the kinda messed up N, nu. See, early Greek alphabets didn’t have two upright strokes in N and M, they had a single upright on the left and a wavy squiggle on top, one dip for N and two dips for M (notice that giving another stroke from the end of N you’d get an approximate M). These two letters look alike because they both represent “nasal” sounds which involve the nose to be voiced. The Greek alphabet wasn’t standardized until the Romans and neither it nor the Latin alphabet had a lowercase until the Byzantines, who also gave Greek its diacritical marks—smooth or rough breathing ( ̓/ ̔), acute or grave accents( ́/ ̀), the circumflex ( ͂), etc. Fun fact: the Greek lowercase iota, ι, got the tittle in Latin alphabets because of an obsolete diacritical mark it stole, something like half an umlaut (ü). J, j, looks like i because after the acquisition of the tittle we started writing consonantal i’s—which sounded more like y’s—like j, an i with a y lower stroke. Yep, i’s in Latin could be consonantal, both initial and mid-position, like Iuvenalis/Juvenal or Aias/Ajax. Consonantal u’s made v’s (again, both initial and mid-position like Juvenal) and the sound made by two consecutive u’s before another vowel—“oowoo”—became the double-u, w, originally written out as “uu.” So if there was a Roman poet UUUUENALIS, we’d render it Vuvuenalis but in time it’d become Wuvenal, which might further morph into Wuvenu and then eventually uwu and you’d exasperatedly wonder “what’s this?”