In Minecraft found a cave with a box and a shield and since then strange things happen?

Ka
3

Me and my friends have recently found a strange room in Minecraft. In this room stood a chest of diamonds and a sign with strange names (see picture). Since then, funny things happen. Skeletons with the head, the person who took slides out of the chest, are spawning all the time. These skeletons have these funny names on the shield, or they are called 'where are my diamonds'. Does anyone know something? Version 1.14

Mu

Since the picture is missing

Ca

Weird thing!

ki

Only someone is trolling you.