How can I lock up Minecraft baby turtles so they can't run away?

So the question might sound a bit stupid, but that's actually my problem😅. I'm not very familiar with Minecraft, but I sometimes play it on my phone. I tried to incorporate turtle eggs to name the baby turtles. I did this with earth because they can crawl under the fences. I always built two earth blocks on top of each other and then built part of the sea. Even above sea level, you have stacked two earth blocks on top of each other. I built a fence inside so I don't step on the eggs. This fence was surrounded by earth again.

I had a door for access. In this construct there was then an egg. I waited a long time. At some point cracks appeared and a few days later the egg was gone. So the baby had hatched. But it wasn't in my enclosure… The enclosure was built in such a way that a full-grown turtle could not have escaped and it was also not built with fences, so how did it escape?! What could I have done differently, or can baby turtles escape anywhere?

Now I just wait until it comes back because turtles always go back to their place of birth. But I would be interested in an answer.

The eggs can also be crushed by monsters…

Nothing should escape there, just light it up better against monsters

Maybe the baby turtles despawned when you were too far away from them

Friendly mobs don't despawn.

Since 2011.

Despawn monsters only.

Bruh and I stand next to a villager in 1.16 without a hobby so that it doesn't despawn

😂🤦🏻♂️

maybe they glitched through the fences