Help me remember a thingy.

Help me out a bit. I remember a feature from before that could track how long a mob has been spawned and could be coded into spawn eggs and /summon commands. It's been about three years since I last used it. What is it called, and can I use it for interaction entities? Something to do with Nether portals, idk I could be wrong. It is something to do with game ticks though I am pretty sure. The version was 1.18 - 1.19, can't be 1.20+