Silk Egg is a poison enemy. At the lowest Threat it has 100 health, hits for 0 and carries 0 armor. It moves at 0, can reach you from 0.5 away, and telegraphs each swing for 1 ticks before it lands, then waits 1 before the next one.

It is part of the shared Demon Gate crowd rather than any one biome, so it can show up almost anywhere.

Killing it pays 0 XP, and it drops something 18% of the time. Crowd control lands on it as immune — it is built into the room and never moves.