Verbs like these are called "Deponent" verbs. Other examples (my grammar text says "a sizable number") are First conjugation, with accent further toward beginning: Έρχομαι I come,
Second conjugation (with several varieties but accent just before ending) Αρνιέμαι I refuse, deny Κοιμούμαι I sleep Κοιμάται Θυμούμαι I remember Θυμάται Λυπούμαι I'm sorry (for) Λυπάται Φοβούμαι I'm afraid Φοβάται
Μιμούμαι I copy Μιμείται Προηγούμαι I precede, come first Προηγείται
I'll look for a better list
As troll1995 writes below, it's a passive voice. Here's a link to a modern Gk verb explanation. You can search for "deponent" to see a list of common deponent verbs, including αισθάνομαι, "I feel": https://moderngreekverbs.com/home.html This verb has an active voice but with a different meaning ("to mention/report") than the middle ("to refer"). So it's not a deponent (no active voice form).